_swab

Swaps bytes.

Syntax

void _swab(
   char *src,
   char *dest,
   int n
);

Parameters

src
Data to be copied and swapped.

dest
Storage location for swapped data.

n
Number of bytes to be copied and swapped.

Return value

The swab function doesn't return a value. The function sets errno to EINVAL if either the src or dest pointer is null or n is less than zero, and the invalid parameter handler is invoked, as described in Parameter validation.

For more information about return codes, see errno, _doserrno, _sys_errlist, and _sys_nerr.

Remarks

If n is even, the _swab function copies n bytes from src, swaps each pair of adjacent bytes, and stores the result at dest. If n is odd, _swab copies and swaps the first n-1 bytes of src, and the final byte isn't copied. The _swab function is typically used to prepare binary data for transfer to a machine that uses a different byte order.

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

For more compatibility information, see Compatibility.

Example

// crt_swab.c

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

char from[] = "BADCFEHGJILKNMPORQTSVUXWZY";
char to[] =   "...........................";

int main()
{
    printf("Before: %s  %d bytes\n        %s\n\n", from, sizeof(from), to);
    _swab(from, to, sizeof(from));
    printf("After:  %s\n        %s\n\n", from, to);
}

Before: BADCFEHGJILKNMPORQTSVUXWZY  27 bytes
        ...........................

After:  BADCFEHGJILKNMPORQTSVUXWZY
        ABCDEFGHIJKLMNOPQRSTUVWXYZ.

See also

Buffer manipulation