函式1：char * strcat ( char * destination, const char * source );

/* strcat example */

#include <stdio.h>

#include <string.h>

int main () {

char str[80];

strcpy (str,"these ");

strcat (str,"strings ");

strcat (str,"are ");

strcat (str,"concatenated.");

puts (str); return 0;

}

輸出是：these strings are concatenated.

這個函式的問題是不夠安全，合併後的字串長度可能超過destination預分配的空間，造成記憶體越界。

函式2：int snprintf( char *buffer, int buff_size, const char *format, ... );

/* snprintf example */

#include <stdio.h>

#include <string.h>

int main () {

char str[10];

strcpy (str,"these ");

snprintf(str+strlen(str),sizeof(str)-strlen(str),"%s", "strings ");

puts (str);

return 0;

}

輸出是:these stri