2.14.7 strcat
Declaration:
char *strcat(char *str1, const char *str2);
Appends the string pointed to by str2 to the end of the string pointed to by str1. The terminating null character of str1 is overwritten. Copying stops once the terminating null character of str2 is copied. If overlapping occurs, the result is undefined.
The argument str1 is returned.