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< c‎ | string‎ | byte
Revision as of 13:47, 10 April 2013 by P12 (Talk | contribs)

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<td>
Defined in header <string.h>
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<td >
void* memcpy( void          *dest, const void          *src, size_t count );
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<td class="t-dcl-nopad"> </td> <td > (until C99) </td> </tr> <tr class="t-dcl ">

<td >
void* memcpy( void *restrict dest, const void *restrict src, size_t count );
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<td class="t-dcl-nopad"> </td> <td > (since C99) </td> </tr> Template:ddcl list end

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.

Contents

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

#include <stdio.h>
#include <string.h>
 
#define LENGTH_STRING 20
 
int main() 
{
    char source[LENGTH_STRING] = "Hello, world!";
    char target[LENGTH_STRING] = "";
    int integer[LENGTH_STRING / 4] = {0};
    int i = 0;
    printf("source: %s\n", source);
    printf("target: %s\n", target);
    printf("integer: ");
    for (i = 0; i < sizeof(integer) / sizeof(integer[0]); ++i) {
        printf("%x ", integer[i]);
    }
    printf("\n");	
    printf("========\n");
 
    /* length + 1 for the string's end-char '\0' */
    memcpy(target, source, strlen(source) + 1); 
    memcpy((char *)integer, source, strlen(source));
    printf("source: %s\n", source);
    printf("target: %s\n", target);
    printf("source(hex): ");
    for (i = 0; i < sizeof(source) / sizeof(source[0]); ++i) {
        printf("%2x ", source[i]);
    }
    printf("\n");
    printf("integer(hex: little-endian): ");
    for (i = 0; i < sizeof(integer) / sizeof(integer[0]); ++i) {
        printf("%x ", integer[i]);
    }
    printf("\n");
    return 0;
}

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 0 0 0 0 0 0 0
integer(hex, little-endian): 6c6c6548 77202c6f 646c726f 21 0

See also

Template:c/string/byte/dcl list memmove