size of an array c

1int a[20];
2int length;
3length = sizeof(a) / sizeof(int);
4

1int prices[5] = { 1, 2, 3, 4, 5 };
2
3int size = sizeof prices / sizeof prices[0];
4
5printf("%u", size); /* 5 */

1int a[17];
2size_t n = sizeof(a)/sizeof(a[0]);
3

1int a[17];
2size_t n = sizeof(a)/sizeof(a[0]);

1int a[]= { 1, 2, 3, 4, 5, 6, 7 };
2int length = sizeof(a) / sizeof(a[0]); //return 7

1#include <stdio.h>#include <stdlib.h>int main(){//a pointer to dynamically allocated memory from the heap is returned.	int *a = (int *) malloc(20 * sizeof(int));for(int i = 0; i < 20; i++)a[i] = i + 1;printf("\nThe contents of the array are: \n");for(int i = 0; i < 20; i++)printf("%d\t", a[i]);realloc(a, 40);for(int