Calloc and Realloc in C

#include<stdio.h>
#include<stdlib.h>
int main()
{
int *ptr;
int i;

ptr=calloc(5,sizeof(int));

if(ptr!=NULL)
{
*ptr=1;
*(ptr+1)=2;
ptr[2]=4;
ptr[3]=8;
ptr[4]=16;
/*ptr[5]=32;*/
ptr=realloc(ptr,7*sizeof(int));
if(ptr!=NULL)
{
printf("Now allocating more memory - \n");
ptr[5]=32;
ptr[6]=64;

for(i=0;i<7;i++)
{
printf("ptr[%d] holds %d\n",i,ptr[i]);
}
realloc(ptr,0);
return 0;
}
else
{
printf("Not enough memory - realloc failed\n");
return 1;
}
}
else
{
printf("Not enough memory - calloc failed\n");
return 1;
}
getch();
return 0;
}