sprintf与snprintf

内容见代码及输出。
代码：

17 int main(int argc,char **argv)
 18 {
 19 char buff1[256]={0};
 20 char buff2[256]={0};
 21 strncpy(buff1, "Hello, buffer 1!", 256);
 22 strncpy(buff2, "Hello, buffer 2!", 256);
 23 sprintf(buff1, "%s, does it work?", buff1);
 24 snprintf(buff2, 256, "%s, does it work?", buff2);
 25 printf("buffer 1: %s\n", buff1);
 26 printf("buffer 2: %s\n", buff2);
 27 return 0;
 28 }


输出：
buffer 1: Hello, buffer 1!, does it work?
buffer 2: , does it work?