How to Find Out Whether a Machine is Big Endian or Little Endian in C/C++?

According to Wiki, the big endian or small endian are two ways of storing bytes of data e.g. 32-bit integer in memory locations.

For Big Endian Representations, the Most Significant Byte (MSB) is stored at lower addresses.

Big Endian Representation in Memory

For Little Endians, it is the opposite, the MSB is stored at higher addresses.

Little Endian Representation in Memory

Test Big/Little Endian in C/C++

We can write a small tool to test Whether a Machine is Big Endian or Little Endian in C/C++. First, we declare a 16-bit integer (short int), which has the value 0x0001, then we gets its pointer and deference it. If the MSB is stored at lower address (e.g. the value that pointer points to), then it is little endian.

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// https://helloacm.com/how-to-find-out-whether-a-machine-is-big-endian-or-little-endian-in-cc/
#include <stdio.h>
 
#define BIG_ENDIAN 0
#define LITTLE_ENDIAN 1
 
int TestByteOrder() {
        short int word = 0x0001;
        char *b = (char *)&word;
        return (b[0] ? LITTLE_ENDIAN : BIG_ENDIAN);
}
 
int main() {
        int r = TestByteOrder();
        printf("%s\n", r == LITTLE_ENDIAN ? "Little Endian" : "Big Endian");
        return r;
}

// https://helloacm.com/how-to-find-out-whether-a-machine-is-big-endian-or-little-endian-in-cc/
#include <stdio.h>

#define BIG_ENDIAN 0
#define LITTLE_ENDIAN 1

int TestByteOrder() {
        short int word = 0x0001;
        char *b = (char *)&word;
        return (b[0] ? LITTLE_ENDIAN : BIG_ENDIAN);
}

int main() {
        int r = TestByteOrder();
        printf("%s\n", r == LITTLE_ENDIAN ? "Little Endian" : "Big Endian");
        return r;
}

To compile it, using e.g. gcc TestByteOrder.c -o TestByteOrder:

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[email protected]:~$ ./TestByteOrder
Little Endian

[email protected]:~$ ./TestByteOrder
Little Endian

Pre-compiled Binaries

• Linux 32-bit (3kb) : gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4
• Windows 32-bit (4kb) : CodeBlocks gcc 4.9.2

Extract the zip and Run TestByteOrder in the console, what is your result? Share yours by commenting below.

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