C language one-dimensional array

1. Definition

An array is composed of a series of elements with the same data type . You can use different data types to define arrays .
Such as ：

int arr[100];// The data type is int Array of 
char ch[100];// The data type is char type 
double nums[100];// The data type is double type 

 Such as arr[100]
arr For array name 
100 Is the number of array elements 

**[] The value in must be constant **

2. Initialize array

Array storage

You can find that the array subscript starts from zero , The address of the array is in 4 byte （int The size of the type variable ） Continuous storage .

Array boundary

When using arrays, you should pay attention to the boundary of arrays , You must ensure that the subscript is a valid value

int arr[5]={
    0};
// Among them is arr[0]=0 arr[1]=0 arr[2]=0 arr[3]=0 arr[4]=0
// The number of array elements is 5  Array index from 0 Start until the number of elements is reduced by one   namely 0,1,2,3,4

Such as arr[5] Beyond the border , After running, because arr[5] Is undefined , The compiler will abort （ Using out of bounds array subscripts will cause the program to change the values of other variables ）.
（ But during the compilation process, the compiler generally does not check for errors , because C The principle of trusting programmers , No boundary checks ）

The array should be initialized or the number of elements should be indicated before use .
The following is the C Several methods commonly used in language to initialize arrays ：

int arr[100]={
    0};// Initialize its 100 The element values are 0
int arr[]={
    1,2,3,4,5,6,7,8,9};// to  arr 1-9 Value 
int arr[5]={
    0,1,2,3,4};// Given number , In the given 5 Elements 
int arr[100]={
    0,1,2,3,4};// after 95 The default value of elements is 0

3. Use of arrays

Assign value to element

If given arr[5] assignment 1,2,3,4,5

int arr[5];

take arr[0] Regard the data type as int A variable called arr[0]

int arr[5];
arr[0]=1;
arr[1]=2;
arr[2]=3;
arr[3]=4;
arr[4]=5;

In use, it can be combined with circulation

for(i = 0;i < 5;i++)
{
    
arr[i]=i;
}