Question

Really dumb question. Here’s my sample code:

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

typedef struct sample {
  int a;
  int b;
} SAMPLE_T;

int main() {
  int i, max = 4;
  for (i = 0; i < max; i++)
  {
     SAMPLE_T * newsamp = (SAMPLE_T *)malloc(sizeof(SAMPLE_T));
     printf("addr: %x\n", &newsamp);
  }
}

I’m trying to ‘create’ a new variable each time I go through the loop, and I thought that this would do the trick, since malloc would create a new variable on the heap. But, it seems I’ve messed something up. Here’s the output:

addr: bfc29c4
addr: bfc29c4
addr: bfc29c4
addr: bfc29c4

Am I not understanding how malloc is working?

Answer 1

The address of newsamp is not changing, which is not surprising. Try:

 printf("addr: %x\n", newsamp)

Also, even though this is obviously just a toy program you really should free the memory before the loop terminates.