C++ Cookbook

10.8. Deleting or Renaming a File

Problem

You have to remove or rename a file, and you want to do it portably, i.e., without using OS-specific APIs.

Solution

The Standard C functions remove and rename, in <cstdio>, will do this. See Example 10-11 for a brief demonstration of them.

Example 10-11. Removing a file

#include <iostream>
#include <cstdio>
#include <cerrno>

using namespace std;

int main(int argc, char** argv) {

   if (argc != 2) {
      cerr << "You must supply a file name to remove." << endl;
      return(EXIT_FAILURE);
   }

   if (remove(argv[1]) == -1) {  // remove() returns -1 on error
      cerr << "Error: " << strerror(errno) << endl;
      return(EXIT_FAILURE);
   }
   else {
      cout << "File '" << argv[1] << "' removed." << endl;
   }
}

Discussion

These system calls are easy to use: just call one or the other with the filename you want to delete or rename. If something goes wrong, the return value is non-zero and errno is set to the appropriate error number. You can use strerror or perror (both declared in <cstdio>) to print out the implementation-defined error message.

To rename a file, you can replace the remove call in Example 10-11 with the following code:

if (rename(argv[1], argv[2])) {
   cerr << "Error: " << strerror(errno) << endl;
   return(EXIT_FAILURE);
}

The Boost Filesystem library also provides the ability to remove or rename a file. Example 10-12 shows a short program for removing a file (or directory, but see the discussion after the example).

Example 10-12. Removing a file with Boost

#include <iostream> ...