C Programming Structures

Question

#include <stdio.h>

struct temp{
 char b1; 
 double a; 
 int f;
};
int main()
{
  struct temp temp1;
  int size = 0;

  size = sizeof(temp1);
}

why size value is 24 instead of 20?... In 32 bit machine.

Advance Thanks...

Do you search before posting your question ? SO is full of duplicate of this question. — Stargateur, Jun 06 '17 at 09:48
Out of interest, why did you think it was 20? That makes me think that you already know something about padding. — Bathsheba, Jun 06 '17 at 09:49
If `double` needs to be aligned to 8 bytes, the entire struct does too, if you’re confused about the 4 end padding bytes. — Ry-, Jun 06 '17 at 09:53

score 0 · Answer 1 · answered Jun 06 '17 at 09:49

0

struct temp{
 char b1;  // 1 byte + 7 bytes padding
 double a; // 8 bytes
 int f;    // 4 bytes + 4 bytes padding
};

This is because of member padding :)

answered Jun 06 '17 at 09:49

Saurav Sahu

1 Answers1