C library function - strncat()


The C library function char *strncat(char *dest, const char *src, size_t n) appends the string pointed to by src to the end of the string pointed to by dest up to n characters long.


Following is the declaration for strncat() function.

char *strncat(char *dest, const char *src, size_t n)


  • dest − This is pointer to the destination array, which should contain a C string, and should be large enough to contain the concatenated resulting string which includes the additional null-character.

  • src − This is the string to be appended.

  • n − This is the maximum number of characters to be appended.

Return Value

This function returns a pointer to the resulting string dest.


The following example shows the usage of strncat() function.

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

int main () {
   char src[50], dest[50];

   strcpy(src,  "This is source");
   strcpy(dest, "This is destination");

   strncat(dest, src, 15);

   printf("Final destination string : |%s|", dest);

Let us compile and run the above program that will produce the following result −

Final destination string : |This is destinationThis is source|