Header File 

string.h, mbstring.h 

Category 

Memory and String Manipulation Routines, Inline Routines 

Prototype 

char *strncat(char *dest, const char *src, size_t maxlen); 

wchar_t *wcsncat(wchar_t *dest, const wchar_t *src, size_t maxlen); 

unsigned char *_mbsncat(unsigned char *dest, const unsigned char *src, size_t maxlen); 

unsigned char *_mbsnbcat(unsigned char *__dest, const unsigned char *__src, _SIZE_T __maxlen); 

Description 

Appends a portion of one string to another. 

strncat copies at most maxlen characters of src to the end of dest and then appends a null character. The maximum length of the resulting string is strlen(dest) + maxlen. 

For _mbsnbcat, if the second byte of 2-bytes character is null, the first byte of this character is regarded as null. 

These four functions behave identically and differ only with respect to the type of arguments and return types. 

Return Value 

strncat returns dest. 

Example  

#include <string.h>
#include <stdio.h>
int main(void)
{
   char destination[25];
   char *source = " States";
   strcpy(destination, "United");
   strncat(destination, source, 7);
   printf("%s\n", destination);
   return 0;
}

Portability