python入门基础代码

python入门基础代码

#查找index函数的帮助

help(str.index)

#for循环和break语句

from math import sqrt

for i in range(2,101):

flag=1

k=int(sqrt(i))

for j in range(2,k 1):

if i%j==0:

flag=0

break

if(flag):

print i

#continue语句,满足条件跳出continue后面的语句sumA=0

i=1

while i<=5:

sumA =i

i =1

if i==3:

continue

print 'i=%d,sum=%d'%(i,sumA)

#循环中的else语句

k=5

for i in range(1,10):

if k==3:

break

else:

print i

#自定义函数/素材1-100间素数

from math import sqrt

def isprime(x):

if x==1:

return False

k=int(sqrt(x))

for j in range(2,k 1):

if x%j==0:

return False

return True

for i in range(2,101):

if isprime(i):

print idef f(x,y=True): #默认参数要放在参数列表的最后

'x and y both correct words or not'

if y:

print x,'and y both correct'

print x,'is Ok'

f(68)

f(68,False)

#传递函数

def addme2me(x):

return(x x)

def self(f,y):

print f(y)

self(addme2me,2.2)

#lambda函数

my_add=lambda x,y:x y

my_add(5,6)

#数据获取与表示

f=open(r'E:\360Downloads\firstpro.txt','w') #新建一个文件f.write('hello,world') #f为对象，write写入文件

f.close()

f=open(r'E:\360Downloads\firstpro.txt','r') #r代表读出

p1=f.read(5) #5代表读出的字节数

p2=f.read()

print p1,p2

f.close

f1=open(r'E:\360Downloads\companies.txt') cname=f1.readlines()

for i in range(0,len(cname)):

cname[i]=str(i 1) '' cname[i]

f1.close

f2=open(r'E:\360Downloads\scompanies.txt','w') f2.writelines(cname)

f2.close()

#网络数据获取

import urllib

r=urllib.urlopen('/')

html=r.read

#序列

#标准类型运算符

'apple'<'banana'

[1,2,3]!=[4,5,6]#值比较

atuple=('ba',126.4)

btuple=atuple

btuple is not atuple#对象身份比较

('86.40'<'122.64') and ('apple'<'banana')#布尔运算

#序列类型运算符

week=['mondy','tuesday','wednesday','thursday','firday','satu day','sunday']

print week[1],week[-

2],'\n',week[1:4],'\n',week[:6],'\n',week[::-1]#序列值的序号是从0开始到N-1或者从-1到N

'apple'*3

'ba' in ('ba','the boeingcompany')

#序列类型转换工厂函数

list('hello,world')#将字符串转成列表

tuple('hello,world')#将字符串转成元组#字符串

s1='''hello

'a'

''b''

world!'''

s1 #三引号可以保持里面字符串的原貌

s2=r'd:\python\a.py'

s2

ccode=['axp','ba','cat','csco','cvx']

cprice=['86.40','122.64','99.44','23.78','115.91']

for i in range(5):

print '%d%8s:%8s' %(i,ccode[i],cprice[i]) #%8s指的占8个字符