check whether CPU is little-endian

checkCPU.c

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

int is_little_endian(void) 
{ 
    union w 
    {
        int  a; 
        char b; 
    } c; 
    c.a = 1; 
    return (c.b == 1); 
}

int main(void)
{
	int ret = is_little_endian();
	printf("%d\n", ret);
}