Thread: why the output of malloc is zero

You can see bellow my code where i try to understand how to use malloc. But, i do not understand something. Why the output of A array is all zero? I thought that calloc does this "trick" and not malloc. Can anyone help me? thanks in advance!

Code:

#include <stdio.h>
#include <stdlib.h>

int main(){
	int i;
	int *A;
		A = malloc(5);
		if(A==NULL){
			printf("Error in allocating space for A array!\n");
			exit(1);
		}else{
			printf("Allocating space for A array succeed!\n");
		}
		// printing the array without any changes
		for(i=0; i<5; i++){
			printf("A[%d]: %d\n", i, A[i]);
		}
		printf("\n");
		// made some changes
		A[0] = 4;
		// again printing the array
		for(i=0; i<5; i++){
			printf("A[%d]: %d\n", i, A[i]);
		}
		printf("\n");
	return 0;
}

If it's zero it's because it happened to be zero and not something caused by malloc. This should be evident by what nimitzhunter said, you are reaching out of the area that you have malloced. In effect only A[0] + one byte is memory you own.

thanks! i understood the difference...