How to avoid Structure Padding in C?

Code:

---

#include <stdio.h>

struct point
{
    int x;
    char y;
    float z;
}var;


int main()
{
    printf("size of structure = %d", sizeof(var));


    return 0;
}

---

size of structure = 12

Lookup the pragmas for your compiler.

For some simple compilers the order will make a difference. Put the biggest items first. As in.

Code:

---

struct point
{
    float z;
    int x;
    char y;
}var;

---

Tim S.

> size of structure = 12
With those three members, it's always going to be 12 no matter how you arrange them.

If you succeed in making it 9 through some pragma, then the compiler will generate very sub-optimal code, because it will have to assume that both the int and float are unaligned. In doing so, it will read each one a byte at a time in order to construct a properly aligned temporary.

Be careful what you're saving.