❮ C Storage Classes C Examples Power Number ❯

C Library Function - `memcpy()`

C Standard Library - <string.h>

Description

The C library function void *memcpy(void *str1, const void *str2, size_t n) copies n bytes from memory area str2 to memory area str1.

Declaration

Here is the declaration for the memcpy() function.

void *memcpy(void *str1, const void *str2, size_t n)

Parameters

str1 -- A pointer to the destination array where the content is to be copied, type-casted to a void* pointer.
str2 -- A pointer to the source of data to be copied, type-casted to a void* pointer.
n -- The number of bytes to be copied.

Return Value

This function returns a pointer to the destination, which is str1.

Example

The following example demonstrates the use of the memcpy() function.

// Copying a string into an array dest
#include <stdio.h>
#include <string.h>

int main ()
{
   const char src[50] = "http://www.tutorialpro.org";
   char dest[50];

   memcpy(dest, src, strlen(src)+1);
   printf("dest = %s\n", dest);

   return(0);
}

Let's compile and run the above program, this will produce the following result:

dest = http://www.tutorialpro.org

Copying 6 consecutive characters starting from the 11th character in s to d:

#include <stdio.h>
#include<string.h>

int main()
{
  char *s="http://www.tutorialpro.org";
  char d[20];
  memcpy(d, s+11, 6); // Copying starting from the 11th character (r), 6 consecutive characters (tutorialpro)
  // Or memcpy(d, s+11*sizeof(char), 6*sizeof(char));
  d[6]='\0';
  printf("%s", d);
  return 0;
}

Let's compile and run the above program, this will produce the following result:

tutorialpro

Overwriting existing data:

#include<stdio.h>
#include<string.h>

int main(void)
{
  char src[] = "***";
  char dest[] = "abcdefg";
  printf("Before memcpy: %s\n", dest);
  memcpy(dest, src, strlen(src));
  printf("After memcpy: %s\n", dest);
  return 0;
}

Let's compile and run the above program, this will produce the following result:

Before memcpy: abcdefg
After memcpy: ***defg

C Standard Library - <string.h>

❮ C Storage Classes C Examples Power Number ❯

C Library Function - memcpy()

Description

Declaration

Parameters

Return Value

Example

C Library Function - `memcpy()`