C/string.h/strncat

strncat: concatenates not more than count characters of str2 to str1 and terminates str1 with a null

//Declaration: char *strncat(char *str1, const char *str2, size_t count); //Return: returns *str1.

 #include <stdio.h>
 #include <string.h>
 int main(void)
 {
   char s1[80], s2[80];
   unsigned int len;
   gets(s1);
   gets(s2);

   len = 79-strlen(s2);
   strncat(s2, s1, len);
   printf(s2);
   return 0;
 }

/* 2 1 12*/

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