append[1]
手写BP（反向传播）算法
⼿写BP（反向传播）算法BP算法为深度学习中参数更新的重要⾓⾊，⼀般基于loss对参数的偏导进⾏更新。
⼀些根据均⽅误差，每层默认激活函数sigmoid（不同激活函数，则更新公式不⼀样）假设⽹络如图所⽰：则更新公式为：以上列举了最后2层的参数更新⽅式，第⼀层的更新公式类似，即上⼀层的误差来⾃于下⼀层所有的神经元，e的更新就是不断建⽴在旧的e 上（这⾥g可以当做初始的e）下⾯上代码：1，BP算法# ⼿写BP算法import numpy as np# 先更新参数，再继续传播# layers：包括从输⼊层到输出层，每层参数为：连接权重w，阈值b，输出y。
类型为np.array# 对于输⼊层，w和b随便是啥，反正不⽤，只需y即原始输⼊# 基于激活函数sigmoid# loss为均⽅误差def bp(layers,labels,lr=0.001):# 翻转layers，反向传播reversed_layers=layers[::-1]# 输出层output_w,output_b,output_y=reversed_layers[0]g=np.array([output_y[j]*(1-output_y[j])*(labels[j]-output_y[j]) for j in range(len(labels))])# 最后⼀层更新较为特殊，先进⾏更新delta_w=np.empty(shape=(output_w.shape[0],output_w.shape[1]))# 上⼀层输出ylast_y=reversed_layers[1][2]for h in range(output_w.shape[0]):for j in range(output_w.shape[1]):delta_w[h,j]=lr*g[j]*last_y[h]delta_b=-lr*gnew_w=output_w+delta_wnew_b=output_b+delta_breversed_layers[0][0]=new_wreversed_layers[0][1]=new_b# 从倒数第⼆层到第⼆层进⾏更新，每次取3层进⾏计算，由公式知，需⽤到上⼀层输出即下⼀层权重for i in range(1,len(reversed_layers)-1):# 下⼀层wnext_w=reversed_layers[i-1][0]out_w,out_b,out_y=reversed_layers[i]# 上⼀层ylast_y=reversed_layers[i+1][2]# 更新辅助量，意思即上⼀层每个神经元的误差都由下⼀层所有神经元的误差反向传播，体现在这⾥内循环e=np.empty(shape=(len(out_b),1))for h in range(len(out_b)):temp=0for j in range(next_w.shape[1]):temp+=next_w[h,j]*g[j]e[h]=out_y[h]*(1-out_y[h])*tempdelta_w=np.empty(shape=(out_w.shape[0],out_w.shape[1]))for h in range(out_w.shape[0]):for j in range(out_w.shape[1]):delta_w[h,j]=lr*e[j]*last_y[h]delta_b=-lr*eout_new_w=out_w+delta_wout_new_b=out_b+delta_breversed_layers[i][0]=out_new_wreversed_layers[i][1]=out_new_bg=np.copy(e)return layers以上假设每个神经元的输出为⼀个实数y值2，构建测试构建平⾯上的点（x,y），将y是否⼤于0作为划分，进⾏训练。
Mathematica入门教程
In[1]:=378/123，系统会输出 Out[1]:=126/41，如果想得到近似解，则应输入
In[2]:=N[378/123,5],即求其 5 位有效数字的数值解，系统会输出 Out[2]: =3.073
全新版《大学英语综合教程》第1册练习答案Appendix1上海外语教育出版社
全新版《⼤学英语综合教程》第1册练习答案Appendix1上海外语教育出版社Appendix IKey to Exercises (Units 1-8)Unit 1Part I Pre-reading TaskScript f or the recording:Have you ever heard of the pop singer, John Lennon? Here he is singing a song he wrote for hi s son. It's called Beautiful Boy.Close your eyesHave no rearThe monster s toneHe's on the run and your daddy's hereBeautiful, beautiful, beautifulBeautiful boyBeautiful, beautiful, beautifulBeautiful boyBefore you go to sleep Say alittle prayer1 John Lennon (1940-1980): First became famous as a singer and guitarist in the Beatles, a British rock group, writing many of their most successful hits. Later he left the group, but continued to be popular as a singer and songwriter.Every day in every wayIt's getting better and betterBeautiful, beautiful, beautifulBeautiful boyBeautiful, beautiful, beautifulBeautiful boyOut on the ocean sailing awayI can hardly waitTo see you come of ageBut I guess we’ll both just have to be patient‘Cause it's a long way t o go A bard row to hoe Y esit's a long way to goBut in the meantimeBefore you cross the streetTake my bandLife is what happens to youWhile you're busy making other plansBeautiful, beautiful, beautifulBeautiful boyBeautiful, beautiful, beautifulBeautiful boyBefore you go to sleep Say a littleprayer Every day in every way It'sgetting better and better1 A hard row to hoe: To hoe is to use a special farming tool, a hoe, to clear small weeds and break up the surface of the soil. The row referred to is a row of plants.Appendix I- $9 -Beautiful, beautiful, beautifulBeautiful boyDarling, darling, darlingDarling SeanYou've just heard John Lennon singing a lullaby to his son Sean. A lullaby is a song we sing to help babies to go to sleep. So he tells Sean "Close your eyes, have no fear, your Daddy's here." Then he looks into the future. He sees his son setting out on life's adventure:Out on the ocean sailing awayAnd he can hardly wait to see his son grow up, to reach eighteen when he comes of age and celebrates becoming an adult. But he knows they'll both have to be patientCause it'a long way to go Ahard row to hoeGrowing up can be difficult. At times it can, as we say, be a hard row to hoe. It's a phrase we use to describe any difficult task. But if growing up is sometimes hard, it is also full of surprises. Things happen when we least expect them:Lire is what happens to youWhile you're busy making other plansI think you'll find the stories you are going to read in this unit show that John Lennon was right: growing up can be quite an adventure, full of the unexpected.As for John Lennon, sadly he never did live to see his son grow up and come of age, for John was shot dead by a madman in New York while Sean was still only five years old.- 90 -Appendi x IPart II Text AText organizationl.Paragraphs Headings1Baker's feelings about English courses2Baker's impression of his new English teacher3 A topic that attracts Baker's attention4Vivid memories the title brought back5Baker's sudden desire to write about that topic6Anticipating punishment7Mr. Fleagle's announcement8Classmates' response to the essay9What Baker discovered2.Parts Paragraphs Main IdeasPart i Paras 1-2Baker was bored by everything associated with English courses, including essay writing.Part II Paras 3-5Baker found himself attracted by one particular topic and wrote about it for his own joy.Part III Paras 6-9The experience of writing the essay helped him discover his talent for writing and realize what he wished to do inlife.Appendi x I- 91 -VocabularyI. 1. 1) arguments2) put ... down3) sequence4) rigid5) tedious6) hold back7) reputation8) distribute9) off and on10) vivid11) associate ... with12) congratulations13) finally14) turn in/turn out15) tackle2. 1) George has been assigned to the newspaper's Paris office.2)There is a possibility that his wish to become a writer will come true.3)She had a clear image of how she would look in twenty years' time.4)When the officer gave the command the soldiers opened fire.5)As long as people keep buying bikes we'll keep turning them out.3. 1) Mr. Green is very dull as a lecturer. He's rigid and old fashioned, and doesn't seem to havethe faintest idea of how to inspire. I always get bored with / by his lectures.2)Alan's essays are long and tedious to read. What's more, his arguments are often based onout of date ideas.3)I was pleasantly surprised at my ability to compose an essay that the professor chose toread to the class. It was without doubt one of the happiest moments in my school career, but I did my best to avoid showing pleasure. When the professor offered me his congratu-lations, however, I could hardly hold back a smile.II. Synonyms in Context1. composed2. severe3. agony4. extraordinary5. recall6. command7. was violating8. anticipateIII. Collocation1. at2. for3. of4. with5. as6. about7. to8. in, in- 92 - Appendi x I9. from 10. on/uponStructure1. 1) Russell Baker is reported to live today with his wife in Virginia. 2) They are said to be building another bridge across the river.3) Only a few students in Mr. Parker's composition class are said to have really captured the essence of the essay.4) Those love poems were believed to have been composed by an English poet of the sixteenth century.2. 1) as you suggested 2) as I told you to■3) exactly as I was4) as you have described them to me Comprehensive ExercisesI. Cloze(A)1. hold back 3. tedious 5. recall7. arguments9. turn out/turn in (B) 1. that 3. black 5. at7. different 9. On11. answer 13. wrong 15. ThusII. TranslationSusan lost her legs because of / in a car accident. For a time, she didn't know how to face2. congratulations 4. scanned 6. vivid8. off and on 10. career2. after4. kids/children 6. for/of 8. So 10. she12.assignment/book 14.proved 16myselfApp endi x I - 93 -up to the fact that she would never ( be able to) walk again.One day, while scanning (through ) books, a true story caught her eye/she was attracted by a true story. It gave a vivid description of how a disabled girl became a writer. Greatly inspired. Susan made up her mind to read as much as she could, and what's more, she wanted to write stories about her own childhood. Susan began to feel that she, too, would finally be able to lead a useful life.Part III TextBComprehension Check l.b 2. a 3. c 4. c 5.b 6. cTranslation(参见 Appendix HI) Language Practice 1. on purpose 3. comprises 5. assumed 7. generally 9. represent 11. voluntary 13. moti oned 15. decentPart IV Theme-related Language Learning TasksMod el paperA memorable ExperienceOn the morning of the college entrance test I rode a bike to the school where I would take the2. in advance 4. adjusting to 6. think up 8. clashes 10. evil12. in the meantime 14. appeal- 94 -App endi x Iexamination.Less than halfway between my house and the school, disaster struck. My bike hit a nail and the front tyre went flat. I pushedthe bike along the streets, looking for a repair shop. Minutes passed but still there was none to be found. When I looked at my watch, I went wild with worry: there were only fifteen minutes left before the examination began, and the nearest bus stop was a long way off. Not knowing what to do, I stood still by the side of the road, tears welling up in my eyes. Then a car pulled in and I heard a voice asking what the matter was. When he heard my story, the driver offered me a lift. Thank to his kindness, I arrived just in time. And so here I am today.( 157 words)Unit 2Part I Pre-reading TaskScript for the recording:Just what are friends for? To have fun with, of course, to share in the good times. Yet most people would say that a real friend is more than just a fair weather fri end. A fair weather fri end? A fair weather friend is someone who's happy to stay with you when things are going well but leaves as soon as trouble arrives, while a good friend, a true friend, is one who'll stand by you when you find yourself in difficulties. That's certainly what the American pop singer Dionne W arwick thinks. As she tells her friend... you can always count on me,For sure, that's what friends are for,For good times,an bad times,I’ 11 be on your side forevermore.But she sings it better than I can say it. So let's listen to her as she sings her song That's What Friends Are For.Appendix I- 95 -That's What Friends Are ForDionne WarwickAnd I never thought I'd reel this way And asfar as I'm concerned I'm glad I got the chanceto sayThat I do believe I love youAnd if I should ever go away,Well, then close your eyes and try,To feel the way we do today,/And then if you can remember,Keep smiling, keep shining,Knowing you can always count on me,For sure, that's what friends are for,For good times> and had times,I'll he on your side forevermore,That's what friends are for.Well, you came and opened meAnd now there's so much more I seeAnd so by the way, I thank youAnd then for the times we're apart,Well, then close your eyes and knowThese words are coming from my heartAnd then it you can remember,Keep smiling, keep shining,Knowing you can always count on me,For sure, that's what friends are for,For good times, and had times,I'll he on your side forevermore,That' s what friends are for,Keep smiling, keep shining,Knowing you can always count on me,For sure that's what friends are for,For good times, and had times,I'll he on your side forevermore,- 9t? -Appendix IThat's what mends are tor, Keep smiling, keepshining, Knowing you can always count on me,For sure, that's what friends are tor. For goodtimes, and bad times, I'll be on your sideforevermore, That' s what friends are f or.Part II Text APoints for Discussion1. a) He sounded as if he had a cold or something.b)"Thanks," I said, "but I don't want to read your mail. That's pretty personal."c)... the first sentence reminded me of myself: "I've been meaning to write for some time, butI've always postponed it."d)It then went on to say that he often thought about the good times they had had together whenthey both lived in the same neighborhood.e)He shook his head: "Time."f)"This is a good part here," I said. "Where it says, your friendship over the years has m eant anawful lot to me, m or e than I can say because I'm not good at saying things like that." I found myself nodding in agreement. "That must have made you feel good, didn't it?"g)"I know I'd like to receive a letter like that from my oldest friend."lext Organization1. 1) The story begins with the cab driver reading a letter.2)The letter Tom wrote to his friend Ed.3)Their conversation was centered on the lifelong friendship between the driver and Old Ed.4)The author got to learn more about their friendship by reading the letter himself.2.Parts Paragraphs Main IdeasPart One Paras 1-20From a conversation with the cab driver the author learnedhow much he regretted failing to keep up correspondenceAppendi x I- 97 -with his old friend Ed.Part Two Paras 21-35 Reading the l etter by himself, the author l earned more about the lifelong friendship between the driver and Old Ed. Part ThreePara 36The driver's experience urged the author to reach for his pen.VocabularyI. 1. 1) absolutely3) every now and then 5) destination 7) mostly 9) right away 11) or something 13) went by 15) keep in touch2. 1) It seemed that his failure in the examination was still on his mind.2) He was completely choked up by the sight of his team losing in the final minutes of the game.3) She was so lost in study that she forgot to have dinner.4) Something has come up and I am afraid I won't be able to accomplish the project on time. 5) The cost of equipping the new hospital was estimated at $2 million.3. 1) A couple of flights at Pudong Airport were postponed this morning because of the awfulweather. It is estimated that over one thousand passengers were held up.2) My professor assigned me some reference books on computers to read. Unfortunately they are not available in our school library. I am kind of worried about it.3) Michael is not much of a teacher. He often skips from one subject to another so it is difficult for his students to follow him. Besides he just lets them go ahead with exercises without making sure they have understood what they are expected to do. II. Collocation1. to2. for3. at4. from5. in *6. to7. on8. with2) available4) are urging/urged 6) know ... by heart 8) hangs out 10) reunion 12) practically 14) going ahead- 9$ -Appendix IIII. Usage1. more or less2. kind of/sort of3. Something4. kind of/sort of5. more or less6. or somethingStructure1. 1) may/might as well watch2)may/might as well pour out3)may/might as well walk4)may/might as well buy2. 1) She looks as if she is worried about it.2)It smells as if it is fresh.3)It sounds as if it is Chinese.4)It feels as if it is made of silk. Comprehensive ExercisesI. Cloze(A)1. choked up3. practically5. correspondence 7. destination9. Mostly11. absolutely(B)1. how3. but5. to7. reply/answer 9. asking11.touch13. pieces15. check 2. awful4. neighborhood 6. available8. reunion 10. postponing2. himself4. So6. long8. from10. when 12. for14. go16. outApp endi x I- 99 -II. T ranslationIt is not easy to keep in touch with friends when they are far away. This is certainly true in my case.It has been a couple of years since I left my old neighborhood and all the friends I had there. I've been meaning to write to them but something or other comes up and I just don't seem to find the time. Now I have kind of lost touch with them. They are always on my mind, however, and I think I will certainly make an effort to keep up correspondence with them in future.Part III Text BComprehension Checkl.d 3. a 5. c 7. d 2. b 4. d 6. dTranslation(参见Appendix III) language Practice1. stuff3. dragging5. get rid of7. was peering/peered 9. swung11. extent13. draw on15. Worse still 2. uneasy4. highlight6. despair8.soaked10. in good shape 12. rescue14. let... down- 100 - Appendix IPart IV Theme-related Language Learning TasksModel paperOld Friend,I've been meaning to write for some time, but I've always postponed it. Y ou know what I'm like, always putting things off till tomorrow. And writing was never my strong point. But looking out the window just now at the kids playing outside reminded me of when we were their age. All sorts of memories, like the time Tim Shea broke the window, the Halloween that we tiedOld Mr. Parker's gate, and when Mrs. Culver used to keep us after school, came flooding back. What a great time we spent hanging out together. Come to think of it, time was just about all we did have to spend in those days.But time flies. I began the letter with "Old Friend" because that's what we've become over the years—old friends. And there aren't many of us left. Which makes those who are all the more precious. Y ou in particular. Y our friendship over the years has meant an awful lot to me, more than I can say because I'm not good at saying things like that.Anyway, we've been out of touch for far too long. So I thought you'd like to know that I was thinking of you. We really must try to get together soon. Why not come to visit? Y ou know you're always welcome.Y our Old Friend,Tom PS If you see Tim Shea remind him he never did replace that ball of mine he broke the window with!(245 words)A ppendi x I- 101 - Unit 3Part I Pre-reading TaskScript for the recording:This unit begins with an article on science. Before you read it, let me tell you something about its author, Stephen Hawking.Hawking is perhaps the most well-known scientist since Einstein. Like Einstein his work tackles the big questions, questions such as How did the universe begin? Why is the universe the way it is? and How will it end? He is now working on what is sometimes known as the 'theory of everything.' Among other things, this promises to explain what caused the Big Bang that started the universe.But it is not simply the power of Hawking's mind that has led to his fame. For what many people find most striking about him is the contrast between the strength of his mind and the weakness of his body. For for many years Hawking has suffered from an illness that has left him unable to move and to speak normally.Born in England in 1942, Hawking had a normal childhood, and it was not until he was a student at university that his illness started to affect him. Hospital tests showed he was suffering from a disease that weakens control over the muscles. The disease gets worse with time and there is no known cure. But Hawking did not lose heart. As he says, "although there was a cloud hanging over my future, I found, to my surprise, that I was enjoying life more than before. I began to make progress with my research, and I got engaged to a girl called Jane Wilde. That engagement changed my life. It gave me something to live for."Hawking started research at Cambridge and went on to hold the same post that another great scientist, Newton, once held. Over the years his condition has worsened, but even when he finally lost the ability to speak, he managed to get round the problem. He now uses a computer that enables him to select words which are then turned into speech. "The only trouble," the English scientist says, "is that it gives me an American accent!"- 102 -Appendix IPart II Text AT ext Organization1.Parts Paragraphs Main IdeasPart One Paras 1-3 To make informed decisions about change, the public needs a basic understanding of science.Part Two Paras 4-6 What can be done to educate the public about science. Part ThreePara 7With an informed public, human civilization will survive.2. 1) The importance of the teaching of science in schools. 2) The role mass media can play, especially what television can do.Vocabularyinquired in terms of tend precise grasped sufficient conveyin two mindsWinning the match today has ensured their team a place in the Cup Final. Susan was not informed of the reasons why she was dismissed. These computer games entertain as well as educate the learner. No living thing can do without air and water. The election is likely to be held in June.The film's appeal lies in not only the entertainment it provides to the audience but also the questions it raises about the possible contact between human beings and alien civilizations. 2) The decision on the new project is made on the basis of scientific study. The project is2) brief 4) cut...off 6) anyway 8) moreover 10) in the form of 12) initiative 14) fit into1 ? 1) 3)5)7)9)11 13 152 1) 2) 3) 4) 5) 31)Appendix I- 103 -likely to succeed despite the fact that we do not have sufficient funds at the moment.3) True it is hard to make accurate predictions (预⾔), but the steady growth of the informa-tion industry ensures that this line of products will be highly profitable. II. Prefixation 1. regained 3. undersupplied 5. precondition 7.mispronounced2. undecided 4. disabled 6. foresight8. enrichIII. Antonyms 2. 1)majority 3) increased 5) local 7) wrong2) accepted4)weaknesses 6) late 8) falseStructure1) My income is now twice as much as I used to earn two years ago.2) I am wearing only half as much as I usually do because of the warm weather.3) If you had spent half as much time on your studies as your elder sister did, you could have made the honor roll.4) I could eat/could have eaten as much again if the doctor had not told me to go on a diet.1) As is shown by the growth rate of GDP in the last two decades, China's reform and open policy is a great success. 2) As is predicted by some newspapers, there will be a substantial cut in tax on imported cars inGood bad modern ancient Rich poor forget remember Dry wet go come Agree differ young oldAttack defend simple difficult Colored colorless like v., n. dislike Long short likely unlikely Early late trust distrust- 104 -A pp endi x 1the coming year.3)As is proved by the records, China's human rights situation has been steadily improving over4)The failure of the joint venture was not, as was assumed by outsiders, because of lack ofcapital, but because of poor management.Comprehensive ExercisesI. Cloze(A)1. attitude2. highly3. informed4. bring... about5. rate6. sufficient7. put across 8. proportion9. Hence 10. ensure11. audience(B)1. which2. how3. Besides4. that/which5. discoveries6. Another7. through 8. other9. an 10. affect11. imagine/tell 12. may13. supply 14. around15. make 16. liveII. TranslationIt is hard to imagine how our forefathers could do without so many conveniences that modern technology has brought about. Back then only a small proportion of the population en-joyed some comforts. The majority didn't even have sufficient food, not to speak of/let alone the privilege of being educated. However, many people blame modern technology for the problems it has created. They want to slow down the rate of progress. But no one can put the clock back. The best we can do is to make informed decisions as to the direction in which technology is to develop.I105 Part III TextBComprehension Checkl.d 3. a5.c 7. b 2. b 4. c 6. aTranslation(参见Appendix III)Language Practice 1. outcome 3. yield5. worn down 7. amount9. proposed 11. Somehow 13. process 15. challenges2. frustrating 4. Failure6. conclusions 8. professional 10. evaluating 12. bulk14. step by stepPart IV Theme-related Language Learning TasksModel paperHow Science Changes Our LivesScience has certainly changed our lives, bringing benefits to some and hardships to others. Computers, for example, have provided some with the comfort of working from home while at the same time throwing others out of work as their jobs are automated. In the future changes are likely to be even much greater as science reaches out to shape life itself. New organisms (有机体) are already being engineered. New genetically modified crops promise benefits from higher yields and less use of harmful chemicals.But once again we cannot be sure that science will only change our lives for the better. The possibility remains that some modern Frankenstein may carelessly or deliberately let loose a new and。
python123答案
求绝对值【光】-数字类型#69291n = eval(input()) #eval可保持输入类型print(abs(n)) #abs()是求绝对值函数Hello world【光】-字符串#69306s = input()print('欢迎你,{}'.format(s))成绩转换【光】-分支结构#69380#用户输入百分制的学生成绩，成绩大于或等于60的判定为“pass”，否则为“fail”#用于初学，不考虑异常数据score = eval(input())if score >= 60:print('pass')else:print('fail')绩点计算【光】-分支结构#69396score = {'A':4.0,'A-':3.7,'B+':3.3,'B':3.0,'B-':2.7,'C+':2.3,'C':2. 0,'C-':1.5,'D':1.3,'D-':1.0,'F':0.0}gpaSum,creditSum = 0,0while True:s = input()if s == '-1':breakelif s in score.keys():credit = float(input())gpaSum = gpaSum + score[s] * creditelse:print('data error')creditSum = creditSum +creditgpaAve = gpaSum / creditSumprint('{:.2f}'.format(gpaAve))求e的近似值B 【光】-循环结构#69445threshold=eval(input())item=1e=1f,n=1,0while item>=threshold:n=n+1f=f*nitem=1/fe=e+itemprint("{:.8f}".format(e))今天是第几天【光】-分支结构#69374#year = int(input())#month = int(input())#day = int(input())year,month,day = map(int,input().split('/'))months = (0,31,59,90,120,151,181,212,243,273,304,334)if 0 <= month <= 12:sum = months[month - 1]else:print('data error')sum += dayleap = 0if (year % 400 == 0) or ((year % 4 == 0) and (year % 1 00 != 0)): #判断闰年leap = 1if (leap == 1) and (month > 2):sum += 1print('{}年{}月{}日是{}年第{}天'.format(year,month,day,year,sum))身高测算【光】-分支结构#69395x=int(input())y=int(input())g=input()if g=="男":h=(x+y)*1.08/2print(int(h))elif g=="女":h=(x*0.923+y)/2print(int(h))else:print("无对应公式")百钱买百鸡A 【光】-循环结构#69428for x in range(1,20): #x不为0，初值设1for y in range(1,34): #y不为0，初值设1z=100-x-yif z != 0 and z%3==0 and 5*x+3*y+z//3==100:print(x,y,z)杨辉三角【光】-列表元组#69499# 输出杨辉三角import mathnum=eval(input()) #输入想要计算的杨辉三角形的阶数n=len(str(int(math.factorial(num)/(math.factorial(int(num/2))*math.factorial(num-int(num/2)))))) #判断最大的数字位数ls=[]def yhlist(m): #计算每行的数字global lsif m==1:ls.append(1)return lselse:ls.insert(0,0)ls.append(0)for i in range(m):ls[i]=(ls[i]+ls[i+1]) #肩上两个数字和return lsfor i in range(1,num+1):lt=yhlist(i).copy() #创建新列表，防止旧值被改变s=0print(" "*(n*(num+1-i)),end="") #控制输出格式for j in range(i):s=s+lt[j]print("{:{}}".format(lt[j],n),end=(" "*n)) #最大位数作为间隔与数字输出长度print(" "*(n*(num+1-i)),end="")print()字符串去重排序【光】-字典集合#69520s = input()sets = set(s)lists = list(sets)lists.sort()print(''.join(lists))。
期末复习题
选择题1.表达式500/10的结果是：A）‘500/10’B）500/10C）50D）50.0正确答案：D2.以下关于字符串类型的操作的描述，错误的是：A）str.replace(x,y)方法把字符串str中所有的x子串都替换成yB）想把一个字符串str所有的字符都大写，用str.upper()C）想获取字符串str的长度，用字符串处理函数str.len()D）设x = ’aa’，则执行x*3的结果是‘aaaaaa’正确答案：C3.设str = 'python'，想把字符串的第一个字母大写，其他字母还是小写，正确的选项是：A）print(str[0].upper()+str[1:])B）print(str[1].upper()+str[-1:1])C）print(str[0].upper()+str[1:-1])D）print(str[1].upper()+str[2:])正确答案：A4.执行以下程序，输入p，输出结果是：k = 0s = input('请输入q退出：')if s == 'q':k += 1continueelse:k += 2breakprint(k)A）2B）请输入q退出：C）3D）1正确答案：A5.以下表达式，正确定义了一个集合数据对象的是：A）x = { 200, ’flg’, 20.3}B）x = ( 200, ’flg’, 20.3)C）x = [ 200, ’flg’, 20.3 ]D）x = {‘flg’: 20.3}正确答案：A6.以下程序的输出结果是：ss = list(set("jzzszyj"))ss.sort()A）['z', 'j', 's', 'y']B）['j', 's', 'y', 'z']C）['j', 'z', 'z', 's', 'z', 'y', 'j']D）['j', 'j', 's', 'y', 'z', 'z', 'z']正确答案：B7.以下程序的输出结果是：ls =list({'shandong':200, 'hebei':300, 'beijing':400})print(ls)A）['300','200','400']B）['shandong', 'hebei', 'beijing']C）[300,200,400]D）'shandong', 'hebei', 'beijing'正确答案：B8.以下选项中不可用作Python标识符的是A）3.14B）姓名C）__Name__D）Pi正确答案：A9.Python可以将一条长语句分成多行显示的续行符号是：A）\C）;D）‘正确答案：A10.运行以下程序，输出结果的是：print(5/2)A）3B）2C）2.5D）2.50正确答案：C11.下面代码的输出结果是：TempStr = "Pi=3.141593"print(TempStr[3:-1])A）3.14159B）3.141593C）Pi=3.14D）3.1416正确答案：A12.for或者while与else搭配使用时，关于执行else语句块描述正确的是A）仅循环非正常结束后执行（以break结束）B）仅循环正常结束后执行C）总会执行D）永不执行正确答案：B13.下面代码的输出结果是for n in range(400,500):i = n // 100j = n // 10 % 10k = n % 10if n == i ** 3 + j ** 3 + k ** 3:print(n)A）407B）408C）153D）159正确答案：A15.字典d={'Name': 'Kate', 'No': '1001', 'Age': '20'}，表达式len(d)的值为A）12B）9C）6D）3正确答案：D16.元组变量t=("cat", "dog", "tiger", "human")，t[::-1]的结果是A）{'human', 'tiger', 'dog', 'cat'}B）['human', 'tiger', 'dog', 'cat']C）运行出错D）('human', 'tiger', 'dog', 'cat')正确答案：D17.关于Python的列表，描述错误的选项是A）Python列表是包含0个或者多个对象引用的有序序列B）Python列表用中括号[]表示C）Python列表是一个可以修改数据项的序列类型D）Python列表的长度不可变的正确答案：D19.s = " Python", 能够显示输出Python 的选项是：A）print(s[0:-1])B）print(s[-1:0])C）print(s[:6])D）print(s[:])正确答案：D20.字符串s = "I love Python"，以下程序的输出结果是：s = "I love Python"ls = s.split()ls.reverse()print(ls)A）'Python', 'love', 'I'B）Python love IC）NoneD）['Python', 'love', 'I']正确答案：D21.以下程序的输出结果是：s=''ls = [1,2,3,4]for l in ls:s += str(l)print(s)A）1,2,3,4B）4321C）4,3,2,1D）1234正确答案：D22.以下关于程序控制结构描述错误的是：A）单分支结构是用if保留字判断满足一个条件，就执行相应的处理代码B）二分支结构是用if-else根据条件的真假，执行两种处理代码C）多分支结构是用if-elif-else处理多种可能的情况D）在Python的程序流程图中可以用处理框表示计算的输出结果正确答案：D23.ls = [1,2,3,4,5,6], 以下关于循环结构的描述，错误的是：A）表达式for i in range(len(ls)) 的循环次数跟for i in ls 的循环次数是一样的B）表达式for i in range(len(ls)) 的循环次数跟for i in range(0,len(ls)) 的循环次数是一样的C）表达式for i in range(len(ls)) 的循环次数跟for i in range(1,len(ls)+1) 的循环次数是一样的D）表达式for i in range(len(ls)) 跟for i in ls 的循环中，i 的值是一样的正确答案：D24.以下程序的输出结果是：j = ''for i in "12345":j += i + ','print(j)A）1,2,3,4,5B）12345C）‘1,2,3,4,5,’D）1,2,3,4,5,正确答案：D25.以下程序的输出结果是：a = 30b = 1if a >=10:a = 20elif a>=20:a = 30b = aelse:b = 0print('a={}, b={}'.format(a,b))A）a=30, b=1B）a=30, b=30C）a=20, b=20D）a=20, b=1正确答案：D26.以下关于组合数据类型的描述，错误的是：A）集合类型是一种具体的数据类型B）序列类似和映射类型都是一类数据类型的总称C）python 的集合类型跟数学中的集合概念一致，都是多个数据项的无序组合D）字典类型的键可以用的数据类型包括字符串，元组，以及列表正确答案：D27.以下程序的输出结果是：ls1 = [1,2,3,4,5]ls2 = [3,4,5,6,7,8]cha1 = []for i in ls2:if i not in ls1:cha1.append(i)A）(6, 7, 8)B）(1,2,6, 7, 8)C）[1,2,6,7,8]D）[6, 7, 8]正确答案：D29.以下程序的输出结果是：frame = [[1,2,3],[4,5,6],[7,8,9]] rgb = frame[::-1]print(rgb)A）[[1, 2, 3], [4, 5, 6]]B）[[7, 8, 9]]C）[[1,2,3],[4,5,6],[7,8,9]] D）[[7, 8, 9], [4, 5, 6], [1, 2, 3]]正确答案：D31.以下程序的输出结果是：for i in "CHINA":for k in range(2):print(i, end="")if i == 'N':breakA）CCHHIINNAAB）CCHHIIAAC）CCHHIAAD）CCHHIINAA正确答案：D32.以下程序的输出结果是：x= 10while x:x -= 1if not x%2:print(x,end = '')else:print(x)A)86420B)975311C)97531D）864200正确答案：D33.以下关于组合类型的描述，错误的是：A)可以用大括号创建字典，用中括号增加新元素B)嵌套的字典数据类型可以用来表达高维数据C)字典的pop 函数可以返回一个键对应的值，并删除该键值对D)空字典和空集合都可以用大括号来创建正确答案：D34.以下程序的输出结果是：x = ['90','87','90']n = 90print(x.count(n))A)1B)2C)NoneD)0正确答案：D36.s = "the sky is blue"，表达式print(s[-4:], s[:-4]) 的结果是：A)the sky is blueB)blue is sky theC)sky is blue theD)blue the sky is正确答案：D37.以下对Python 程序缩进格式描述错误的选项是：A)不需要缩进的代码顶行写，前面不能留空白B)缩进可以用tab 键实现，也可以用多个空格实现C)严格的缩进可以约束程序结构，可以多层缩进D)缩进是用来格式美化Python 程序的正确答案：D38.定义x=2.6，表达式int(x) 的结果是：A)3B)2.6C)2.0D)2正确答案：D39.以下程序的输出结果是：for i in reversed(range(10, 0, -2)):print(i,end=" ")A)0 2 4 6 8 10B)12345678910C)9 8 7 6 5 4 3 2 1 0D)2 4 6 8 10正确答案：D40.以下程序的输出结果是：for i in "the number changes":if i == 'n':breakelse:print( i, end= "")A)the umber chagesB)thenumberchangesC)theumberchages正确答案：D41.以下程序的输出结果是：for i in range(3):for s in "abcd":if s=="c":breakprint (s,end="")A）abcabcabcB)aaabbbcccC)aaabbbD)ababab正确答案：D42.以下关于字典类型的描述，错误的是：A）字典类型是一种无序的对象集合，通过键来存取B）字典类型可以在原来的变量上增加或缩短C）字典类型可以包含列表和其他数据类型，支持嵌套的字典D）字典类型中的数据可以进行分片和合并操作正确答案：D43.以下程序的输出结果是：ls =list("the sky is blue")a = ls.index('s',5,10)A）4B）5C）10D）9正确答案：D44.以下程序的输出结果是：d = {"zhang":"China", "Jone":"America", "Natan":"Japan"}for k in d:print(k, end="")A）ChinaAmericaJapanB）zhang:China Jone:America Natan:JapanC）“zhang””Jone””Natan”D）zhangJoneNatan正确答案：D45. Python 中对变量描述错误的选项是：A)Python 不需要显式声明变量类型，在第一次变量赋值时由值决定变量的类型B)变量通过变量名访问C)变量必须在创建和赋值后使用D)变量PI 与变量Pi 被看作相同的变量正确答案：D46.运行以下程序，输出结果的是：str1 = "Nanjing University"str2 = str1[:7] + " Normal " + str1[-10:]print(str2)A)Normal UB)Nanjing NormalC)Normal UniversityD)Nanjing Normal University正确答案：D47.以下语句执行后a、b、c的值是：a = "watermelon"b = "strawberry"c = "cherry"if a > b:c = aa = bb = cA)watermelon strawberry cherryB)watermelon cherry strawberryC)strawberry cherry watermelonD)strawberry watermelon watermelon正确答案：D48.以下关于Python 的控制结构，错误的是：A)每个if 条件后要使用冒号（：）B)在Python 中，没有switch-case 语句C)Python 中的pass 是空语句，一般用作占位语句D)elif 可以单独使用正确答案：D49.以下程序的输出结果是：Da = {"北美洲":"北极兔","南美洲":"托哥巨嘴鸟","亚洲":"大熊猫","非洲":"单峰驼","南极洲":"帝企鹅"}Da["非洲"] = "大猩猩"print(Da)A)('北美洲': '北极兔', '南美洲': '托哥巨嘴鸟', '亚洲': '大熊猫', '非洲': '大猩猩', '南极洲': '帝企鹅')B)['北美洲': '北极兔', '南美洲': '托哥巨嘴鸟', '亚洲': '大熊猫', '非洲': '大猩猩', '南极洲': '帝企鹅']C){"北美洲":"北极兔","南美洲":"托哥巨嘴鸟","亚洲":"大熊猫","非洲":"单峰驼","南极洲":"帝企鹅"}D){'北美洲': '北极兔', '南美洲': '托哥巨嘴鸟', '亚洲': '大熊猫', '非洲': '大猩猩', '南极洲': '帝企鹅'}正确答案：D50.以下关于列表操作的描述，错误的是：A)通过append 方法可以向列表添加元素B)通过extend 方法可以将另一个列表中的元素逐一添加到列表中C)通过insert(index,object) 方法在指定位置index 前插入元素objectD)通过add 方法可以向列表添加元素正确答案：D51.以下关于字典操作的描述，错误的是：A)del 用于删除字典或者元素B)clear 用于清空字典中的数据C)len 方法可以计算字典中键值对的个数D)keys 方法可以获取字典的值视图正确答案：D52.下程序的输出结果是：a = ["a","b","c"]b = a[::-1]print(b)A）['a', 'b', 'c']B）'c', 'b', 'a'C）'a', 'b', 'c'D）['c', 'b', 'a']正确答案：D53.以下关于列表和字符串的描述，错误的是：A）列表使用正向递增序号和反向递减序号的索引体系B）列表是一个可以修改数据项的序列类型C）字符和列表均支持成员关系操作符（in）和长度计算函数（len()）D）字符串是单一字符的无序组合正确答案：D631.假设将单词保存在变量word 中，使用一个字典类型counts={}，统计单词出现的次数可采用以下代码：A)counts[word] = count[word] + 1B)counts[word] = 1C)counts[word] = count.get(word,1) + 1D)counts[word] = count.get(word,0) + 1正确答案：D632.以下程序的输出结果是：lcat =["狮子","猎豹","虎猫","花豹","孟加拉虎","美洲豹","雪豹"]for s in lcat:if "豹" in s:print(s,end="")continueA)猎豹花豹美洲豹雪豹B)猎豹C)雪豹D)猎豹花豹美洲豹雪豹正确答案：D636.以下程序的输出结果是：ls = ["石山羊","一角鲸","南极雪海燕","竖琴海豹","山蝰"] ls.remove("山蝰")str = ""print("极地动物有",end="")for s in ls:str = str + s + ","print(str[:-1],end="。
数据科学技术与应用 1-数据分析基础
否
离婚
9.5
…
…
…
无法偿还债务 （是/否） 否 否 否 否 是
…
#读取数据 data = pd.read_csv(filename, index_col = 0, header = None) #准备数据 X = data.loc[ :, 1:3 ].values.astype(float) y = data.loc[ :, 4].values.astype(int)
• 帮助数据分析找到行动方向
• 数学
• 数学家是团队中解决问题的人 • 负责建立概率统计模型、进行信号处理，模式识别，
预测性分析
• 计算机科学
• 数据科学是由计算机系统来实现的 • 负责建立正确的系统架构，设计技术路线，选用开发
平台和工具，最终实现分析目标
数据科学流程
• 数据科学研究内容包括研究数据理论、数据处理以及数据管 理等
Python编译环境
• Python集成开发环境
• 如IDLE、Pycharm、Spyder等
IDLE
• 轻量级的交互式解释环境 • Python解释器附带 • Shell界面 - 交互运行
• “Anaconda Prompt”->命令行 界面->键入“IDLE”
• 文件运行界面
• Shellle”
• “数据分析”术语表示数据科学的核心工作
• 通过对已知数据的探索以及对未来情况的建模，数据分析让预测成 为可能
问题描述 目标和需求
问题
采集、存储、清洗、 标准化、转化
数据准备
数据探索
图形统计 考察数据
报表、仪表盘、图形 发布至报告或应用系统
结果可视 化
预测建模 统计模型
python的append用法
python的append用法Python的append用法是Python语言中常用的一种将某元素加入到列表中的方法。
使用append方法可以快速完成像添加元素、去重、追加、统计等操作。
本文将详细介绍Python的append用法，包括语法结构、一些典型的应用示例。
首先，让我们来看一下Python的append用法的语法结构。
append()函数原型如下：list.append(x)，其中list为列表，x为要追加的元素，可以是列表、字符串、数值、元祖等类型。
而此处x 不能是包含多个元素的列表，而只能是单个元素，否则会报错。
下面我们来看一下一些典型的应用示例：1、将元素添加到列表末尾：list = [1,2,3]list.append(4)print(list) #输出：[1,2,3,4]2、追加另一个列表：list_a = [1,2,3]list_b = [4,5,6]list_a.append(list_b)print(list_a) #输出：[1,2,3,[4,5,6]]3、去除列表中重复元素：list_a = [1,2,3,2,3,4]list_b = []for item in list_a:if item not in list_b:list_b.append(item)print(list_b) #输出：[1,2,3,4]4、统计列表中元素出现的次数：list_a = [1,2,3,2,3,4]count_dict = {}for item in list_a:if item not in count_dict:count_dict[item] = 1else:count_dict[item] +=1print(count_dict) #输出：{1: 1, 2: 2, 3: 2, 4: 1} 以上就是Python的append用法的典型应用示例，它的实际应用涉及的范围更广阔，有助于我们更好地处理冗长的列表操作。
全国青少年信息素养大赛python选做题模拟一卷
全国青少年电子信息智能创新大赛python·选做题模拟一卷1. 下面程序执行完毕后，最终的结果是？（）a=[34,17,7,48,10,5]b=[]c=[]while len(a)>0:s=a.pop()if(s%2==0):b.append(s)else:c.append(s)print(b)print(c)A、[34, 48,10] [17, 7, 5]B、[10, 48, 34] [5, 7, 17]C、[10, 48, 34] [17, 7, 5]D、[34, 48, 10] [5, 7, 17]2. 以下程序的运行结果是？（）l =["兰溪","金华","武义","永康","磐安","东阳","义乌","浦江"]for s in l:if"义"in s:print(s)A、兰溪金华武义B、武义义乌C、武义D、义乌3. 以下程序的输出结果是？（）ls = [1,2,3]lt = [4,5,6]print(ls+lt)A、[1,2,3,4,5,6]B、[1,2,3,[4,5,6]]C、[4,5,6]D、[5,7,9]4. 列表listV = list(range(10)),以下能够输出列表listV中最小元素的是？（）A、print(min(listV))B、print(listV.max( ))C、print(min(listV()))D、print(listV.revrese(i)[0])5. 以下程序的输出结果是（）。
a = tuple('abcdefg')print(a)A、('a', 'b', 'c', 'd', 'e', 'f', 'g')B、 B、['a', 'b', 'c', 'd', 'e', 'f', 'g']C、['abcdefg']D、'abcdefg'6. 运行如下程序，结果是？（）l=[1,"laowang",3.14,"laoli"]l[0]=2del l[1]print(l)A、[1, 3.14, 'laoli']B、[2, 3.14, 'laoli']C、["laowang",3.14, 'laoli']D、[2,"laowang",3.14,]7. 关于列表s的相关操作，描述不正确的是？（）A、s.append():在列表末尾添加新的对象B、s.reverse():反转列表中的元素C、s.count():统计某个元素在列表中出现的次数D、s.clear()：删除列表s的最后一个元素8. 关于以下代码，描述正确的是？（）a = 'False'if a:print('True')A、上述代码的输出结果为True。
Python考试(有答案)
一、填空题1.Python程序文件的扩展名是（）A..pythonB..pytC..ptD..P.y.2.下述标识符中,（）不是Python语言的保留字.A.falseB.TrueC.notD.elif3.s-'HelloPython',以下选项表示"Python"（）A.s[5:10)B.s[6:11]C.s[5:)D.s[6:]表达式1//2+3.68的值是（）A.4B.3.68C.4.18D.表达式错误5.x=3,y=2,执行x,y=y,x后x.y的值是（）A.2,3B.3,2C.2.2D.3.3.6.（）不是Python 逻辑运算.A.andB.orC.notD.XOr7.一个中文字符和一个英文字符在Python 中对应的字符个数是（）A.1.1B.1,2C.2,1D.2.28.下列字符串合法的是（）A."Hello"Python"!"B.'Hello"Python"!.C.’Hello'Python'!'D."Hello"Python'!’9.下列能够根据逗号分割字符串str的是（）A.str.split(‘ , ’);B.str.split(" , ")；C.stesplit(" . ")D.str.split（）；10.若定义:def fun(a=3):return a-1.fun(fun(fun()))的运行结果是（）A.1B.OC.-1D.2二、阅读程序,写出程序运行结果1.str="hello world".str2=str.split()i=0print(len(str2))while i<len(str2):print( str2[i] )i=i+12.numl,num2=12,18.fori in range(min(numl,num2),0,-1):if num1 %i=0 and num200%i=0:print(i,numl*num2//i)break3.a=(2020,"2020",22.3,2020,2020)print(a);4.deffun(listl=[]):listl.append(1)return listl.a=fun()b=fun().print(a,b);.5.d=("201801":"小明”,”201802":"小红,"201803":"小白"d.ge('201803’)三、程序改错1.下列程序获取输入的一个整数n,计算并打印1+2+**********的和。
python3练习题100道，孰能生巧，之前要想一个下午的内容，马上就有了答案
python3练习题100道，孰能⽣巧，之前要想⼀个下午的内容，马上就有了答案第1章字符串练习题1.1交换已知a的值为“hello”，b的值为“world”，如何交换a和b的值？得到a的值为“world”，b的值为“hello”a="hello"b="world"#⽅式1a,b=b,aprint("a的值："+a+"; b的值："+b)#⽅式2a="hello"b="world"c=aa=bb=cprint("a的值：{}; b的值{}".format(a,b))1.2回⽂回⽂的定义：“回⽂”就是正读倒读都是⼀样的如奇数个“98789”，这个数字正读是“98789”倒读也是“98789”。
偶数个数字“3223”也是回⽂数。
字母“abcba”也是回⽂。
判断⼀个字符串是否是回⽂字符串，是打印True，不是打印False。
a=input("请输⼊⼀个字符串：")print(a)flag=Truefor i in range(len(a)//2):if a[i]!=a[-i-1]:flag=Falseprint("{}不是⼀个回⽂字符串;".format(a))breakif flag:print("{}是⼀个回⽂字符串;".format(a))1.3字符串切割已知⼀个字符串为“hello_world_huihui”，如何得到⼀个队列["hello","world","huihui"]a="hello_world_huihui"print(a.split("_"))1.4拼接字符串有个列表['hello', 'world', 'huihui'] 如何把列表⾥的字符串串联起来得到字符串"hello_world_huihuia=['hello', 'world', 'huihui']aa=""for i in a:aa+=iaa += "_"print(aa[:-1]) 1.5 替换字符把字符串s中的每个空格替换成"%20"输⼊：s="We are happy."s="We are happy."ss=s.replace(" ","%20")print(ss)1.6 九九乘法表打印99乘法表for i in range(1,10):for j in range(1,i+1):print("{}*{}={}".format(j,i,i*j),end=" ")print()1.7字符下标找出单词"welcome" 在字符串"Hello,welcome." 中出现的位置，找不到返回-1从下标0开始索引a="welcome"b="Hello,welcme.welcome.."n=0if a in b:for i in b:if i!=a[0]:n+=1else:end=len(a)+n# print(end)if a==b[n:end]: #[6:14]print("单词{} 在{}的第{}位出现；".format(a,b,n))breakn+=1else:print("单词{} 未在{}中出现；".format(a,b)) 1.8 统计字符出现的次数统计字符串"Hello,welcome to my world." 中字母w出现的次数统计单词my出现的次数a="Hello, welcome to my world."b='w'# ⽅式⼀：# if b in a:# # count=0# # for i in a:# # if i==b:# # count+=1# # print("{}在字符串{}中,出现了{}次；".format(b, a,count))# # else:# # print("{}未出现在字符串{}中；".format(b,a))# ⽅式⼆：#直接将m替换为my即可count=0 while True: if b in a: a=a.replace(b,'',1) count+=1 else: break print("{}在字符串{}中,出现了【{}】次；".format(b, a,count))1.9 统计每个字符出现的次数题⽬：输⼊⼀个字符串str，输出第m个只出现过n次的字符， 如在字符串gbgkkdehh中，找出第2个只出现1次的字符，输出结果：d # a="gbgkkdehh"a=input('请输⼊⼀个字符串：')m=3n=2b={}count=0for i in a:if i not in b.keys():b[i]=1else:b[i]+=1print(b)for i in b.keys():if count==m:print(i)break1.10 判断字符a含b判断字符串a="welcome to my world" 是否包含单词b="world"，包含返回True，不包含返回False a="welcome to my world"b="world"if b in a:print("True")else:print("False")1.11 查找字符⾸次出现位置输出指定字符串A在字符串B中第⼀次出现的位置，如果B中不包含A，则输出-1从0开始计数A="hello"B="hi how are you hello world,hello yoyo !"A = "hello"B = "hi how are you hello world, hello yoyo !"n=0if A in B:b=B.replace(A,'=',1)print(b)for i in b:if i!='=':n+=1else:print("{}在字符串{}中第⼀次出现的位置是 {}".format(A,B,n))else:print(-1)1.12 查找字符串最后⼀次出现位置输出指定字符串A在字符串B中最后出现的位置，如果B中不包含A，则输出-1从0开始计数A="hello"B = "hi how are you hello world, hello yoyo !" A = "hello"B = "hi how are you hello world,hello yoyo !"n=0count=0print(len(B))while A in B:n=B.index(A)B=B.replace(A,'',1)count+=1# print(n)print(n+(count-1)*len(A))1.13判断奇数偶数 给定⼀个数a，判断⼀个数字是否为奇数或偶数a=int(input("请输⼊任意⼀个整数："))# print(a,type(a))if a%2==0:print("偶数")else:print("奇数")1.14判断⼀个姓名是否姓王 输⼊⼀个姓名，判断是否姓王a="王五"b="⽼王"a="⽼王五"if a[0]=="王":print("{} 姓‘王’".format(a))else:print("{} 不姓'王'".format(a))1.15 判断是不是数字如何判断⼀个字符串是不是纯数字组成a="123456"b="yoyo123"#⽅式1import rea="123456"b=re.findall('\d',a)if len(a)==len(b):print("{} 是纯数字；".format(a))else:print("{} 不是纯数字；".format(a))#⽅式2a="12345c6"if a.isdigit():print("数字字符串")else:print("⾮数字字符串")1.16 字符串⼤⼩写转换将字符串 a="This is string example....wow!" 全部转成⼤写字符串 b="Welcome To My World"全部转成⼩写a="This is string example....wow!"print(a.upper())print(a.lower())1.17 字符串去掉⾸尾空格将字符串a=" welcome to my world "⾸尾空格去掉 a=" welcome to my world "print(a.strip())print('abcab'.strip('a'))1.18字符串去掉左边指定空格或字符将字符串a = " welcome to my world ！"左边的空格去掉a = " welcome to my world ！ "print(a.lstrip())1.19字符串去掉右边指定空格或字符将字符串a = " welcome to my world ! "右边的空格去掉a = " welcome to my world!"print(a.rstrip())print(a.rstrip("!"))1.20 去除字符串⾥⾯所有的空格将字符串a = " welcome to my world ! "⾥⾯的所有空格都去掉a = " welcome to my world ! "print(a.replace(' ',''))1.21字符串去重后排序s = "ajldjlajfdljfddd"，去重并从⼩到⼤排序输出"adfjl"s = "ajldjlajfdljfddd"rs=[]for i in s:if i not in rs:rs.append(i)# rs=sorted(rs) #列表排序⽅式1rs.sort()s="".join(rs)print(rs,s)1.22字符串去重保留顺序s = "ajldjlajfdljfddd"，去重保留原来的顺序，输出"ajldf"s = "ajldjlajfdljfddd"rs=""for i in s:if i not in rs:rs+=iprint(rs)1.23画菱形题⽬打印出如下图案（菱形）:n=7for i in range(n//2+1):print(' '*(n//2-i)+'*'*(2*i+1))#3,1; 2,3; 1,5;;0,7;;for i in range(n//2-1,-1,-1):print(' '*(n//2-i)+'*'*(2*i+1))1.24 输⼊⼀个正整数，判断是⼏位数题⽬给⼀个不多于5位的正整数，要求：⼀、求它是⼏位数，⼆、逆序打印出各位数字。
python 综合试卷(含答案)-2020-2021学年高中信息技术浙教版(2019)必修1
Python程序设计综合测试试卷总分：100分时间：90分钟一、单项选择题（每题2分，共40分）1. 以下不是Python中的关键字是（）A.breakB.ifC.inD.true2. 下列转义字符中，属于“回车”含义的是（）A.\nB.\rC.\tD.\a3.下列变量名中哪个是合法的（）A._test&B.breakC.My WordD.my_son4. X=3；Y=4；Z=5；执行X,Z,Y=Z,Y,X后print（X,Y,Z）的结果（）A.3 4 5B.4 3 5C.5 3 4D.错误5.在Python中用来做注释的符号是（）A.%B.#C.！D.：6.在Python中不能用for循环遍历的类型是（）A.字符串B.列表C.字典D.数值7. print("ab" +"c"*2)的结果为（）A.abc2B.ababcC.abccD.abccab8.字典的相邻键值对之间用（）分割A.逗号B.冒号C.分号D.句号9. print([1,2]*2)的结果为( )A.[2,4]B.[1,2,1,2]C.错误D.[1,2][1,2]10.以下表达式的结果为True的是（）A.‘ab’>‘bc’B.’ab’==abC.100<’99’D.0!=’’11.下列哪个函数可以创建一个元组（）A.tuple()B.set()C.list()D.input()12.用于跳出本层循环的控制语句是（）A.continueB.breakC.whileD.pass13.在Python中运行c=set('school');print(len(c))的结果是（）A.6B.5C.4D.314.While循环中，若循环9次，则需要进行（）次比较A.9B.10C.11D.815.幂运算运算符为（）。
A.*B.**C.%D.//16. 优先级最高的运算符为（）。
全国青少年编程Python编程四级试卷1及答案
全国青少年编程Python编程四级试卷1及答案1.若A,B,C,D,E这5个元素依次顺序进栈，则下列不会出现的出栈顺序是（）。
A．E。
A。
B。
C。
D B．A。
B。
C。
D。
E C．B。
C。
D。
E。
A D．E。
D。
C。
B。
A答案：B解析：因为栈是后进先出的，所以最后一个进栈的元素一定是最先出栈的，依次类推，所以选项B是不可能出现的。
2.以下步骤描述的分形方式是（）。
步骤1：把闭区间平均分为三段，去掉中间的1/3部分段，留下剩余两个闭区间；步骤2：将剩下的两个闭区间各自平均分为三段，同样去掉中间的区间段，这时剩下四段闭区间；步骤3：重复删除每个小区间中间的1/3段，迭代至区间无穷小。
A．XXX曲线 B．谢尔宾斯基三角形 C．XXX三分集D．XXX迭代答案：B解析：这是谢尔宾斯基三角形的生成方式。
3.下方排序算法的时间复杂度为（）。
x = 0y = 1for i in range(n):x += ifor j in range(n):y *= jA．O(n) B．O(n2) C．O(logn) D．O(1)答案：O(n2)解析：两个for循环嵌套，时间复杂度为O(n^2)。
4.下列属于分类算法的是（）。
A．K-Means算法 B．DBSCAN算法 C．Koch曲线递归算法 D．贝叶斯算法答案：A、B、D解析：K-Means、DBSCAN和贝叶斯算法都是分类算法，而Koch曲线递归算法是一种分形算法。
5.对于顺序存储的栈和队列，进行插入运算的时间复杂度为（）。
A．O(n) B．O(n2) C．O(logn) D．O(1)答案：D解析：顺序存储的栈和队列在插入时只需要将元素放在数组的末尾，时间复杂度为O(1)。
6.下列满足短任务优先且不会发生饥饿现象的调度算法是（）。
A．先来先服务 B．高响应比优先 C．时间片轮转 D．非抢占式短任务优先答案：D解析：非抢占式短任务优先算法会优先选择执行短任务，而且不会发生饥饿现象。
append的用法总结大全
append的用法总结大全（学习版）编制人：__________________审核人：__________________审批人：__________________编制学校：__________________编制时间：____年____月____日序言下载提示：该文档是本店铺精心编制而成的，希望大家下载后，能够帮助大家解决实际问题。
文档下载后可定制修改，请根据实际需要进行调整和使用，谢谢!并且，本店铺为大家提供各种类型的经典范文，如英语单词、英语语法、英语听力、英语知识点、语文知识点、文言文、数学公式、数学知识点、作文大全、其他资料等等，想了解不同范文格式和写法，敬请关注!Download tips: This document is carefully compiled by this editor.I hope that after you download it, it can help you solve practical problems. The document can be customized and modified after downloading, please adjust and use it according to actual needs, thank you!In addition, this shop provides various types of classic sample essays, such as English words, English grammar, English listening, English knowledge points, Chinese knowledge points, classical Chinese, mathematical formulas, mathematics knowledge points, composition books, other materials, etc. Learn about the different formats and writing styles of sample essays, so stay tuned!append的用法总结大全append的意思append的简明意思vt. 附加；添加英式发音 [ə'pend] 美式发音 [ə'pend]append的词态变化为:过去式: appended 过去分词: appended 现在分词: appending 第三人称单数: appendsappend的具体用法如：Appends the specified element of List ( optional operation ).在列表尾部添加指定元素 ( 可选操作 ).在此句中append表示添加的意思Cannot append pages from the selected document because it does not have any pages.因为所选文档中没有页面,所以无法附加页面.在此句中append表示附加的意思append的用法例句Therefore, we may say that women are part of Chinese Daoism rather than anything appended.通过上述分析, 我们可以说:在道教里,妇女不再是“添加”的成分,而是中国道教的有机组成部分.在此句中append表示添加的意思Added components are appended to the end of the list.所添加的组件会附加到列表的结尾.在此句中append表示添加的意思It is appended super amino acid and soy albumen.特别添加超级氨基酸—大豆肽蛋白.在此句中append表示添加的意思But we have another profile a filter that appends the hostname to the Request URI.但是,我们还有其他的配置,过滤器,附加的主机名的请求.在此句中append表示附加的意思The program will append this snapshot to a log file.计划将把这张快照附加到一件登录文件.在此句中append表示附加的意思。
python向列表添加元素的方法
python向列表添加元素的方法Python是一种简单易学的编程语言，广泛应用于数据处理、数据分析、人工智能等领域。
在Python中，列表（List）是一种常用的数据结构，用于存储一组有序的数据。
本文将介绍Python中向列表添加元素的几种方法。
1.使用append()方法添加元素列表对象有一个内置的方法append()，可以在列表末尾添加新的元素。
例如，我们有一个空列表my_list，可以通过以下方式向其添加元素：```pythonmy_list = []my_list.append('apple')my_list.append('banana')my_list.append('orange')```执行完上述代码后，my_list中的元素为['apple', 'banana', 'orange']。
可以看到，使用append()方法，可以将元素依次添加到列表的末尾。
2.使用insert()方法在指定位置添加元素除了在末尾添加元素，我们还可以使用insert()方法在列表的指定位置插入新的元素。
insert()方法接受两个参数，第一个参数是要插入的位置（索引值），第二个参数是要插入的元素。
例如，我们有一个列表my_list，可以通过以下方式在索引为1的位置插入新的元素：```pythonmy_list = ['apple', 'orange']my_list.insert(1, 'banana')```执行完上述代码后，my_list中的元素为['apple', 'banana', 'orange']。
可以看到，使用insert()方法，我们可以在指定位置插入新的元素。
3.使用extend()方法添加多个元素如果我们想一次性添加多个元素到列表中，可以使用extend()方法。
试题python软件编程等级考试(一级)编程实操题练习
试题python软件编程等级考试(一级)编程实操题练习一、选择题1．以下Python中变量的命名正确的是（）A．1a=4B．print=5C．_A=2D．a+b=32．Python语言属于（）A．自然语言B．汇编语言C．机器语言D．高级语言3．python3解释器执行not 1 and 1的结果为（）。
A．True B．False C．0 D．14．在Python中，判断n是否为偶数的表达式是（）A．n/2=0B．n%2==0C．n%2=0D．n/2==05．python语言的特点（）。
A．简单B．免费、开源C．可移植性D．以上都是6．以下（）是python文件A．*.mp3B．*.xls C．*.ppt D．*py 7．下列哪个语句在Python中是非法的？（）A．x = y = z = 1 B．x = (y = z + 1)C．x, y = y, x D．x += y8．小林编写一段文件读写操作代码，文件如图，代码段如下：file=open('ceshi.txt','w')file.write("python is a programming language.")file.close( )file=open('ceshi.txt','r')print(file.read( ))该代码段运行后，输出的结果为（）A．IA Distributed System Based on Python.B．python is a programming language.C．IA Distributed System Based on Python. python is a programming language. D．程序编译错误，不会输出结果9．在python中，想输出一行文字，要用到的函数是（）。
A．input()B．int()C．print()D．float() 10．Python使用函数（）接收用输入的数据A．accept() B．input() C．readline() D．print()11．运行Python程序的过程中出现了如下图错误提示，原因是（）。
编写函数,接收任意多个实数,返回一个元组,其中第一个元素为所有参数的平均值,其他
编写函数,接收任意多个实数,返回一个元组,其中第一个元素为所有参数的平均值,其他【开发该软件的操作系统】：windows10【软件开发环境/开发工具】：PyCharm【编程语言】：Python【开发目的】：这是老师布置的作业啦~ 供初学者参考学习【开发者】：江西农业大学2020级大二学生题目要求：编写一个函数cacluate, 可以接收任意多个数,返回的是一个元组.元组的第一个值为所有参数的平均值, 第二个值是大于平均值的所有数。
（一）代码如下：# 1.定义函数; *args:可变参数def cacluate(*args):# 2.计算平均值; args的数据类型为元组,sum求和average = sum(args) / len(args)# 3.将所有大于平均值数的值存入列表list = []for i in args:if i > average:list.append(i)# 4.将平均值和列表元素存入元组tuple = (average, list)return tuple# nums = input("")print(cacluate(4, 5, 9, 3, 5))结果如下：（二）代码如下：# 1.定义函数; *args:可变参数def cacluate(args):# 2.计算平均值; args的数据类型为元组,sum求和 average = sum(args) / len(args)# 3.将所有大于平均值数的值存入列表list = []for i in args:if i > average:list.append(i)# 4.将平均值和列表元素存入元组tuple = (average, list)return tuplenums = input()# 存储整型k,a,blist = []for item in nums.split():list.append(int(item))print(cacluate(list))结果如下：用逗号隔开：# 1.定义函数; *args:可变参数def cacluate(args):# 2.计算平均值; args的数据类型为元组,sum求和 average = sum(args) / len(args)# 3.将所有大于平均值数的值存入列表list = []for i in args:if i > average:list.append(i)# 4.将平均值和列表元素存入元组tuple = (average, list)return tuplenums = input()# 存储整型k,a,blist = []for item in nums.split(","):list.append(int(item))print(cacluate(list))结果如下：文章：编写一个函数cacluate, 可以接收任意多个数,返回的是一个元组.。
对Python3中列表乘以某一个数的示例详解
[[0], [0]] [[0, 1], [0]]
代码（3）
b = [[] for _ in range(2)] print(b) b[0].append(1) print(b)
输出为：
[[], []] [[1], []]
以上这篇对Python3中列表乘以某一个数的示例详解就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家 多多支持。
a = [0] b = [a for _ in range(2)] print(b) b[0].append(1) print(b)
输出仍为：
[[0], [0]] [[0, 1], [0, 1]]
代码（2）
a = [0] b = [list(a) for _ in range(2)] print(b) b[0].append(1) print(b)
这篇文章主要介绍了python音频生成器的实现示例文中通过示例代码介绍的非常详细对大家的学习或者工作具有一定的参考学习价值需要的朋友们下面随着小编来一起学习学习吧
对 Python3中列表乘以某一个数，如list2 = list1 * 2 得到一个新的列表是list1的元素重复n次，且list1不改变。
但运行如下代码时，得到的新列表b中，b[0]和b[1]的地址相同，即对b[0]进行操作，b[1]也会发生改变。
a = [0] b = [a] * 2 print(b) b[0].append(1) print(b)
输出为：
[[0], [0]] [[0, 1], [0, 1]]
随后尝试以下几种代码：
代码（1）
轮流取棋子的题详解四年级
最近发现了一个有趣的问题，分享一下：王朝和马汉两人做游戏，他们把18粒棋子放在桌上，然后轮流拿，每人每次只能拿1粒、2粒，谁拿到最后一粒谁就获胜，那么有没有办法保证王朝获胜？2. 王朝和马汉两人做游戏，他们把18粒棋子放在桌上，然后轮流拿，每人每次只能拿1粒、2粒或者4粒，谁拿到最后一粒谁就获胜，那么有没有办法保证王朝获胜？第一个题目后手必胜，原因是先手拿1，后手就拿2，先手拿2，后手拿1。
全流程凑3的倍数，最后一定是后手必胜。
第二个题目1+4=5，2+2=4。
跟第一个题目不一样啊？但是1+2=3， 2+4=6（3的倍数），所以我们还能用同样的手法实现，先手拿1或4，后手拿2，先手拿2，后手拿1，必胜。
这两个题目都考察的是观察倍数的方法，如果这个方法不成立怎么样呢？譬如每一个人能拿1，2，4，6中的一种，问谁能赢？这个数可以随便出。
这时候就要要换个思路了：是时候变成一个编程题了！动态规划解决问题。
talk is cheap, show me the code:prob_action=[1,2,4,6] #能拿的策略写这里judge = []res_dict = {}for i in range(len(prob_action)):judge.append(1)def find(x):if x in res_dict:return res_dict[x]if x in prob_action:# if x <= max(prob_action): #如果最后剩2个，你可以选4个一次性全拿走的话就是这个if x not in res_dict:res_dict[x] = 1return 1res_temp = []for i in prob_action:if x < i:continueelse:res_temp.append(find(x-i))for j in res_temp:if j == 0:if x not in res_dict:res_dict[x] = 1return 1if x not in res_dict:res_dict[x] = 0return 0res1 = find(96)print(96,res1) #输出1就是先手必胜，0就是后手必胜。
python基础练习题（题目打印出所有的水仙花数，所谓水仙花数是指一个三位数，其各位数字立。。。
实例013：所有水仙花数
题目 打印出所有的"水仙花数"，所谓"水仙花数"是指一个三位数，其各位数字立方和等于该数本身。例如：153是一个"水仙花数"，因为 153=1的三次方＋5的三次方＋3的三次方。
分析了下，问题不大，偷个懒导入math包：
1 import math
2
3 floor = []
4 for i in range(100,1000):
博客园 用户登录 代码改变世界 密码登录 短信登录 忘记登录用户名 忘记密码 记住我 登录 第三方登录/注册 没有账户, 立即注册
python基 础 练 习 题 （ 题 目 打 印 出 所 有 的 水 仙 花 数 ， 所 谓 水 仙 花 数是指一个三位数，其各位数字立。。。
day8
---------------------------------------------------------------
3 one=int(s[-1])
4 ten=int(s[-2])
5 hun=int(s[-3])
6 if i == one**3+ten**3+hun**3:
7
print(i)
用时间time.perf_countter()多次尝试，发现两种方法运行时间差别不大，但第二种明显可读性更强一点。ຫໍສະໝຸດ 5 list = str(i)
6 sum = 0
7 for j in list:
8
sum += math.pow(int(j),3)
9 if sum == i:
10
floor.append(i)
11 print(floor)
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
附录A C语言运算符表运算符按照优先级大小由上向下排列，在同一行的运算符具有相同优先级。
第二行是所有的一元运算符。
运算符解释结合方式 () [] -> . 括号（函数等），数组，两种结构成员访问由左向右! ~ ++ -- + -* & (类型) sizeof 否定，按位否定，增量，减量，正负号，间接，取地址，类型转换，求大小由右向左* / % 乘，除，取模由左向右 + - 加，减由左向右 << >> 左移，右移由左向右 < <= >= > 小于，小于等于，大于等于，大于由左向右 == != 等于，不等于由左向右 & 按位与由左向右 ^ 按位异或由左向右 | 按位或由左向右 && 逻辑与由左向右 || 逻辑或由左向右 ?= 条件由右向左 = += -= *= /=&= ^= |= <<= >>=各种赋值由右向左 , 逗号（顺序）由左向右关于条件运算符的结合方式，参看第3.4.2节的解释。
附录B C语言速查本附录按照分类描述C语言各方面的特征，对于在本书正文里有详细介绍的东西，这里只给出简单介绍和索引。
在下面介绍中，诸如（2.3.4）之类的写法表示讨论有关问题的章节编号。
1，关键字C语言总共有32个关键字：auto break（4.3.2） case（4.5）char（2.3.3，5.1） const（5.3.5） continue（4.3.2）default（4.5） do（4.3.1） double（2.3.2）else（3.6.1） enum（8.4） extern（5.3.1）float（2.3.2，5.1） for（3.6.3） goto（4.3.2）if（3.6.1） int（2.3.1，5.1） long（2.3.1，5.1）register（5.3.5） return（3.3.1，3.2.3，5.2.4）short（5.1）signed（5.1） sizeof（6.2） static（5.3.4，5.3.5）struct（8.1.1） switch（4.5） typedef（7.6）union（8.3） unsigned（5.1） void（3.3.1，5.2.4）volatile while（3.6.2，4.3.1）注：关键字auto用于说明自动变量，通常不用；volatile（易变的）表示该变量不经过赋值，其值也可能被改变（例如表示时钟的变量、表示通信端口的变量等）。
2，基本类型（2.3，5.1，7）C语言的基本类型包括下面列出的类型，字符类型和各种整型对应的无符号类型，还有各种指针类型，关于指针类型的介绍见第七章。
字符类型短整数类型整数类型长整数类型char short int int long int 浮点数类型双精度浮点数类型长双精度浮点数类型float double long double注：（1）字符类型和所有整数类型都有对应的无符号类型，类型名加unsigned；（2）short int和long int可以分别简写为short和long；（3）unsigned int类型可以简写为unsigned。
3，字面量的书写形式（2.3，5.1）字面量是程序里直接写出的数据，包括各种整数、浮点数、字符和字符串。
整数（各种整型的字面值）由一串数字构成。
第一个数字不是0的是十进制数；以0开头的是八进制数；以0x或0X开头的数字序列表示十六进制数。
加字母 u 或 U 后缀表示无符号整数；加字母 l 或 L 后缀表示长整数。
（2.3.1，5.1）浮点数（float、double和long double类型的字面值）的基本部分包括一个整数部分，一个小数点和一个小数部分。
此后可以有一个指数后缀，其形式是字母e或E后跟一个可以带符号的整数，表示十进制的指数值；最后还可以有一个字母f，F，l 或L作为类型后缀。
f或F表示是float类型的字面量，l或L表示是long double类型，无后缀是double类型。
整数或小数部分两者可以缺一个，小数点和指数部分两者可以缺一个。
（2.3.2，5.1）字符是单引号括起来的一个字符，特殊字符的写法见下面的特殊字符表。
（2.3.3）字符串字面量是由一对双引号界定的一个字符序列，其中可以写各种能直接写出来的字符，以及按下表列出的换意序列方式描述的特殊字符。
以换意序列描述的特殊字符包括：换行符：\n 水平制表符：\t 垂直制表符：\v退格符：\b 回车符：\r 换页符：\f鸣铃符：\a 反斜线符：\\ 问号：\?单引号：\' 双引号：\"任意字符均可以用换意符号（反斜线符）后跟八进制或十六进制表示，形式为：八进制表示：\ooo十六进制表示：\xhh其中ooo表示三位八进制数字，最左一位只能是0到3；hh表示两位十六进制数字，0到9以及A到F或a到f。
4，运算符与表达式所有运算符的优先级及结合方式见附录A。
下面给出各运算符的简单意义，并列出有关它们的讨论所在的章节。
运算符意义章节运算符意义章节()括号，函数[]数组成分 6.1.2->由指针取结构成分8.1.3 .结构成分8.1.2!逻辑非 3.4.3 ~字位取反 5.5++增量 3.7.1 --减量 3.7.1+（一元）正号 2.4.1 -（一元）负号 2.4.1&（一元）取地址7.1.1 (类型)类型强制 2.4.4 sizeof数据或类型的大小 6.2 *算术乘 2.4.1 /算术除 2.4.1 %求余数（取模） 2.4.1+（二元）算术加 2.4.1 -（二元）算术减 2.4.1<<字位左移 5.5 >>字位右移 5.5<小于 3.4.1 <=小于等于 3.4.1>大于 3.4.1 >=大于等于 3.4.1==等于 3.4.1 !=不等于 3.4.1&（二元）字位与 5.5 ^字位异或 5.5|字位或 5.5 &&逻辑与 3.4.3||逻辑或 3.4.3 ?:条件运算符 3.4.2,逗号 3.7.2 =赋值 3.2.2 += -= *= /= %= &= ^= |= <<= >>=各种更新赋值 3.7.3常量表达式：常量表达式用在case后面，描述数组和字段的长度，给枚举常量指定值，给外部变量和局部静态变量提供初始值，给数组、结构变量的成分提供初始值，以及用在条件预处理命令中。
常量表达式在程序加工时被求值，这种表达式里不能包含：赋值运算符、增减量运算符、函数调用、逗号运算符。
对要求整数值的常量表达式，其中的运算对象只能是整数、枚举值、字符、sizeof表达式，浮点数常量必须强制转换到某个整型。
浮点数常量表达式的运算对象只能是整数、浮点数、字符、枚举值、sizeof表达式。
地址常量表达式应表示一个指针值，可以是外部变量、静态变量、函数的地址。
这个指针值可以是通过运算符&作用于外部或静态对象而得到的，或是由数组名、函数名直接创建的。
表达式计算的结果或者就是一个已经说明了的外部或静态变量的地址，或者是一个这种地址加或减一个常数。
创建过程中不应间接访问变量的值。
在预处理命令#if之后的常量表达式中不允许出现sizeof、枚举常量或类型强制。
5，基本控制结构这里列出 C 语言的各种控制结构，并给出简短的解释。
空语句只包含一个分号。
它的执行什么也不做，通常用于在程序中填补位置（3.7.4）。
break;中止语句。
退出最内层的循环语句或者switch语句（4.3.2）。
continue;继续语句。
停止最内层循环体的一次执行，准备开始循环的下次执行（4.3.2）。
goto 标号;转跳语句。
使程序执行立即转到指定标号处。
标号的作用范围是它所在的函数体（4.3.2）。
return;return 表达式;返回语句。
立即结束当前函数的执行，控制返回函数调用处。
第一种形式用于无返回值的函数，第二种形式用于有返回值的函数，在执行时表达式被求值，得到的值转换成函数所要求的返回值类型，作为函数的返回值（3.3.1，3.2.3，5.2.4）。
复合语句在形式上是一对花括号，其中可以有一系列的定义或说明，后跟一系列的语句。
这两部分都可以没有（3.1）。
if (表达式) 语句1if (表达式) 语句1 else 语句2条件语句。
表达式应为算术类型或指针类型。
首先对表达式求值，若得到的值非0就执行语句1部分；若得到值0，有else部分时执行语句2，否则整个条件语句立即结束（3.6.1）。
while (表达式) 语句当循环语句。
表达式应为算术或指针类型。
首先对表达式求值，得到值0时整个循环语句立即结束；得到非0值时执行语句部分，然后重复这整个过程（3.6.2）。
do 语句 while (表达式);首先执行语句，执行完毕后对表达式求值。
当求出的值非0时重复前面的过程；否则整个语句结束。
这里的表达式也必须是算术类型或指针类型的（4.3.1）。
for (初值表达式; 条件表达式; 步进表达式) 语句首先求值初值表达式。
然后顺序地反复做：求值条件表达式，执行语句，求值步进表达式。
一旦某次条件表达式求出值0，整个结构的执行就立即结束。
这里的条件表达式必须是算术类型或指针类型的（3.6.3）。
switch (表达式) {case 常量表达式: 语句序列 case 常量表达式: 语句序列 ...} 这里的复合语句称为switch的体，“case 常量表达式:”称为case标号。
表达式和常量表达式（称为case常量）可以是各种字符类型或整型，一个switch语句的各个case 后的常量表达式的值必须互不相同。
语句的执行过程是：首先求值表达式，用这个值顺序与各case常量表达式的值比较。
发现相等时，就从该标号case后的语句序列开始执行。
switch体中可以有一个default标号，当所有case标号都不匹配时执行转到default 标号处。
如果没有default标号，没有标号匹配时整个语句立即结束。
人们通常在每个语句序列的最后放一个break语句，使语句序列执行完毕时执行能退出switch语句。
如果被执行序列的最后没有break语句，执行将进展到随后的语句（case标号的作用就像是普通标号，只表示一个位置）。
语句序列可以是空（4.5）。
6，变量的定义与说明简单变量定义及初始化问题见（3.2.1，3.2.3，5.3.5），数组定义及初始化见（6.1.1，6.1.2），指针变量的有关问题见（7.1），结构变量、联合变量见（8.1.1，8.3等）。
各种变量有关情况请参看：自动变量（3.2.1，5.3.2，5.3.3），寄存器变量（5.3.5），外部变量（5.3.1，5.3.2，5.3.5），局部静态变量（5.3.4），外部静态变量（5.3.5），常变量（5.3.5）。