memcpy

 

C

Language

Standard Library

Type support

Dynamic memory management

Error handling

Program utilities

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Thread support (C11)

Atomic operations (C11)

 

Strings library

Byte strings

Multibyte strings

Wide strings

 

Null-terminated byte strings

Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (C99)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to numeric formats
atof atoiatolatoll strtolstrtoll	strtoulstrtoull strtofstrtodstrtold
String manipulation
strcpy
strncpy
strcat
strncat
strxfrm
String examination
strlen strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtok
Memory manipulation
memchr
memcmp
memset
memcpy
memmove
Miscellaneous
strerror

 

Defined in header <string.h>
void* memcpy( void          *dest, const void          *src, size_t count );		(until C99)
void* memcpy( void *restrict dest, const void *restrict src, size_t count );		(since C99)

Copies count characters from the object pointed to by src to the object pointed to by dest. If the objects overlap, the behavior is undefined.

Parameters

dest	-	pointer to the memory location to copy to
src	-	pointer to the memory location to copy from
count	-	number of bytes to copy

Return value

dest

Example

Run this code

#include <stdio.h>
#include <string.h>
 
#define LENGTH_STRING 20
 
int main(void)
{
    char source[LENGTH_STRING] = "Hello, world!";
    char target[LENGTH_STRING] = "";
    int integer[LENGTH_STRING / sizeof(int)] = {0};
    printf("source: %s\n", source);
    printf("target: %s\n", target);
    printf("integer: ");
    for (unsigned i = 0; i < sizeof(integer) / sizeof(integer[0]); ++i) {
        printf("%x ", integer[i]);
    }
    printf("\n========\n");
    memcpy(target, source, sizeof source);
    memcpy(integer, source, sizeof source);
    printf("source: %s\ntarget: %s\n", source, target);
    printf("source(hex): ");
    for (unsigned i = 0; i < sizeof(source) / sizeof(source[0]); ++i) {
        printf("%02x ", source[i]);
    }
    printf("\n");
    printf("integer(hex: %s-endian): ", integer[0] == 0x48656c6c ? "big" : "little");
    for (unsigned i = 0; i < sizeof(integer) / sizeof(integer[0]); ++i) {
        printf("%08x ", integer[i]);
    }
    printf("\n");
}

Possible output:

source: Hello, world!
target: 
integer: 0 0 0 0 0 
========
source: Hello, world!
target: Hello, world!
source(hex): 48 65 6c 6c 6f 2c 20 77 6f 72 6c 64 21 00 00 00 00 00 00 00 
integer(hex: big-endian): 48656c6c 6f2c2077 6f726c64 21000000 00000000

See also

memmove	moves one buffer to another (function)
C++ documentation for memcpy