memmove, _fmemmove

Description

Move one buffer to another.

#include <string.h>

void *memmove( void *dest, const void *src, size_t count );

void __far * __far _fmemmove( void __far *dest, const void __far *src,
size_t count );

Remarks

The memmove and _fmemmove functions copy count characters from the source (src) to the destination (dest). If some regions of the source area and the destination overlap, the memmove and _fmemmove functions ensure that the original source bytes in the overlapping region are copied before being overwritten.

The _fmemmove function is a model-independent (large-model) form of the memmove function. It can be called from any point in any program.

Return Value

The memmove and _fmemmove functions return the value of dest.

Compatibility

memmove

Standards:ANSI

16-Bit:DOS, QWIN, WIN, WIN DLL

32-Bit:DOS32X

_fmemmove

Standards:None

16-Bit:DOS, QWIN, WIN, WIN DLL

32-Bit:None

See Also

_memccpy, memcpy, strcpy, strncpy

Example

/* MEMCPY.C. Illustrate overlapping copy: memmove handles it

* correctly; memcpy does not.

*/

#include <memory.h>

#include <string.h>

#include <stdio.h>

char string1[60] = "The quick brown dog jumps over the lazy fox";

char string2[60] = "The quick brown fox jumps over the lazy dog";

/* 1 2 3 4 5

* 12345678901234567890123456789012345678901234567890

*/

void main( void )

{

printf( "Function:\tmemcpy without overlap\n" );

printf( "Source:\t\t%s\n", string1 + 40 );

printf( "Destination:\t%s\n", string1 + 16 );

memcpy( string1 + 16, string1 + 40, 3 );

printf( "Result:\t\t%s\n", string1 );

printf( "Length:\t\t%d characters\n\n", strlen( string1 ) );

/* Restore string1 to original contents */

memcpy( string1 + 16, string2 + 40, 3 );

printf( "Function:\tmemmove with overlap\n" );

printf( "Source:\t\t%s\n", string2 + 4 );

printf( "Destination:\t%s\n", string2 + 10 );

memmove( string2 + 10, string2 + 4, 40 );

printf( "Result:\t\t%s\n", string2 );

printf( "Length:\t\t%d characters\n\n", strlen( string2 ) );

printf( "Function:\tmemcpy with overlap\n" );

printf( "Source:\t\t%s\n", string1 + 4 );

printf( "Destination:\t%s\n", string1 + 10 );

memcpy( string1 + 10, string1 + 4, 40 );

printf( "Result:\t\t%s\n", string1 );

printf( "Length:\t\t%d characters\n\n", strlen( string1 ) );

}

Output

Function: memcpy without overlap

Source: fox

Destination: dog jumps over the lazy fox

Result: The quick brown fox jumps over the lazy fox

Length: 43 characters

Function: memmove with overlap

Source: quick brown fox jumps over the lazy dog

Destination: brown fox jumps over the lazy dog

Result: The quick quick brown fox jumps over the lazy dog

Length: 49 characters

Function: memcpy with overlap

Source: quick brown dog jumps over the lazy fox

Destination: brown dog jumps over the lazy fox

Result: The quick quick quick quick quick quick quick quick

Length: 50 characters