C语言库rename()函数

#include <stdio.h>

int main () {
   int ret;
   char oldname[] = "file.txt";
   char newname[] = "newfile.txt";

   ret = rename(oldname, newname);

   if(ret == 0) {
      printf("file renamed successfully");
   } else {
      printf("Error: unable to rename the file");
   }

   return(0);
}