borl-endian.c

/*
 * This program tests the endian of your system
 */
#include <stdio.h>
#include <stdint.h>

union byte_order {
    uint32_t dword;
    uint8_t  bytes[4];
};

int main(void)
{
    int i;
    union byte_order dw = {
        .dword = 0xAABBCCDD,
    };

    printf("Assigned 0x%X\nRepresented by 0x", dw.dword);
    for (i = 0; i < 4; i++) /* 4 is the sizeof(uint32_t) */
        printf("%X", (unsigned char)dw.bytes[i]);
    putchar('\n');

    if (dw.bytes[0] == (uint8_t)0xAA)
        puts("Your system is BIG ENDIAN");
    else if (dw.bytes[0] == (uint8_t)0xDD)
        puts("Your system is LITTLE ENDIAN");
    else
        puts("I can't tell what your system is...");

    return 0;
}