[C language] detailed explanation of C language to obtain array length

1、 Use sizeof keyword

use sizeof You can get the number of bytes the data type or variable occupies in memory .

Again , use sizeof You can also get the number of bytes the entire array occupies in memory .

Because the type of each element in the array is the same , The number of bytes in memory is the same , So the total number of bytes divided by the number of bytes occupied by an element is the length of the array .

2、 Program instance

#include <stdio.h>

int main(){

    // Define an array 
    int arr[30];

    // Find array length 
    int n = sizeof(arr)/ sizeof(arr[0]);
    printf(" The array length is : n=%d\n",n);
    return 0;
}