How to check whether a system is big endian or little endian?

Question

How to check whether a system is big endian or little endian?

Answer 1

A one-liner with Perl (which should be installed by default on almost all systems):

perl -e 'use Config; print $Config{byteorder}'

If the output starts with a 1 (least-significant byte), it's a little-endian system. If the output starts with a higher digit (most-significant byte), it's a big-endian system. See documentation of the Config module.

Answer 2

In Python:

from sys import byteorder
print(byteorder)
# will print 'little' if little endian

Answer 3

Using Macro,

const int isBigEnd=1;
#define is_bigendian() ((*(char*)&isBigEnd) == 0)

Answer 4

In C, C++

int n = 1;
// little endian if true
if(*(char *)&n == 1) {...}

See also: Perl version

Answer 5

Another C code using union

union {
    int i;
    char c[sizeof(int)];
} x;
x.i = 1;
if(x.c[0] == 1)
    printf("little-endian\n");
else    printf("big-endian\n");

It is same logic that belwood used.

Answer 6

In C

#include <stdio.h> 

/* function to show bytes in memory, from location start to start+n*/
void show_mem_rep(char *start, int n) 
 { 
      int i; 
      for (i = 0; i < n; i++) 
      printf("%2x ", start[i]); 
      printf("\n"); 
 } 

/*Main function to call above function for 0x01234567*/
int main() 
{ 
   int i = 0x01234567; 
   show_mem_rep((char *)&i, sizeof(i));  
   return 0; 
} 

When above program is run on little endian machine, gives “67 45 23 01” as output , while if it is run on big endian machine, gives “01 23 45 67” as output.