C语言英文课件6：数组

6.0 Foreward
1. Question：
Input all students’ score，compute：
Hale Waihona Puke Baidu
1.average；
2.the difference between every one score and average
2. Array
An array is a collectionof individual data values with two distinguishing characteristics:
6.1.2 CITE ELEMENTS OF ARRAY
Arrays have the following syntax, using square brackets to access each indexed value (called an element).
Format: x[i]
In C, indexed value starts with 0. Assigning values to array elements is done by,
y1 3 5 7 9
y[i]=2*i+1;
}
Output result：
for(i=0;i<5;i++)
01
printf("%2d%2d\n",x[i ],y[i]); 2 3
for(i=4;i>=0;i--)
45
printf("%d%d",y[i],x[i]);
67
printf("\n"); }
89 9876543210
Chapter 6 ARRAYS（数组）
6.0 FORWARD 6.1 DECLARATIONS AND CITING OF ONE DIMENSIONAL ARRAYS 6.2 DECLARATIONS AND CITING OF TWO DIMENSIONAL ARRAYS 6.3 CHARACTER ARRAYS AND STRINGS
x[10] = g;
and assigning array elements to a variable is done by,
g = x[10];
[Return]
6.1.3 INITIALIZATIONS OF THE SIMPLE ARRAYS
1. Initialized format:
Data type name of array[constant expression]＝ {list of initial value}
ex.int a[8]; a[0] a[1] a[2] a[3] a[4] a[5] a[6] a[7]
a
Each element in the array is identified by a numeric value called its index.In C,the index numbers for an array always begin with zero and run uo to the array size minus one. Thus,in an array with 8 elements, the index numbers are 0,1,2,3,4,5,6 and 7.
equipollence int a[8]={3,5,6,8,4,0,0,0};
6.1.4 APPLYING EXAMPLES
【ex. 6.1】Compute average and give the level with letter #define N 60 main() { int score[N], i;
a: a[1],a[2],a[3],...a[50]
connected by suffix
a[i]
It is best to think of an array as a sequence of boxes, one box for each data value in the array.Each of the valuesin an array is called an element.
【exercise】Reading the program，write out the result
main() { int x[5],y[5],i;
x[0] x[1] x[2] x[3] x[4]
x0 2 4 6 8
for(i=0;i<5;i++) { x[i]=2*i;
y[0] y[1] y[2] y[3] y[4]
2.explanation： (1)assignment all elements with initial value
ex. int a[5]={3,5,6,8,4}; or int a[ ]={3,5,6,8,4}; (2) assignment part elements with initial value ex. int a[8]={3,5,6,8,4};
ex. int a[8]; a[0] a[1] a[2] a[3] a[4] a[5] a[6] a[7]
a
In C, each array has two fundamental properties:
•The element type •The array size
6.1 DECLARATION AND CITING OF THE
SIMPLE ARRAYS
6.1.1 DECLARATION
Arrays, like other variables in C, must be declared before they are used.
1. DECLARATION FORM
datatype name of array[constant expression]； 2. STORAGE FORM
An array is ordered
An array is homogeneous(类似的)
a1, a2, a3, ... a50
3. Relation between variables
simpleness variable:no connection
ai
between variables
variable suffix variable:variables are