BSWAP(3) Linux Programmer's Manual BSWAP(3)

bswap_16, bswap_32, bswap_64 - reverse order of bytes

#include <byteswap.h>

These macros return a value in which the order of the bytes in their 2-, 4-, or 8-byte arguments is reversed.

These macros return the value of their argument with the bytes reversed.

These macros always succeed.

These macros are GNU extensions.

The program below swaps the bytes of the 8-byte integer supplied as its command-line argument. The following shell session demonstrates the use of the program:

$  ./a.out 0x0123456789abcdef
0x123456789abcdef ==> 0xefcdab8967452301

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <inttypes.h>
#include <byteswap.h>
int main(int argc, char *argv[]) { uint64_t x;
if (argc != 2) { fprintf(stderr, "Usage: %s <num>\n", argv[0]); exit(EXIT_FAILURE); }
x = strtoul(argv[1], NULL, 0); printf("0x%" PRIx64 " ==> 0x%" PRIx64 "\n", x, bswap_64(x));

byteorder(3), endian(3)
2019-03-06 Linux