Multiple files output

As a part of the project I'm working on multiple .ps files need be generated. Note the following:

Code:

outputForGallery( int k) {
     std::string s;
     std::stringstream myOut;
     myOut<<k;
     s=myOut.str();
     std::string fileName="pics/forGallery";
     fileName.append(s); fileName.append(".ps");
     std::ofstream saveFile(fileName);

This means if 0 is passed as a parameter, file with filename forGallery0.ps should be formed(in pics folder). However, I got the following error:

Code:

error: no matching function for call to ‘std::basic_ofstream<char, std::char_traits<char> >::basic_ofstream(std::string&)’
/usr/include/c++/4.4/fstream:623: note: candidates are: std::basic_ofstream<_CharT, _Traits>::basic_ofstream(const char*, std::_Ios_Openmode) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.4/fstream:608: note:                 std::basic_ofstream<_CharT, _Traits>::basic_ofstream() [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.4/iosfwd:84: note:                 std::basic_ofstream<char, std::char_traits<char> >::basic_ofstream(const std::basic_ofstream<char, std::char_traits<char> >&)

Any suggestions on how to avoid this, or other ideas to print files with different filenames are very welcome. I understand that
std:fstream saveFile("something.ps"); would work, but I want this to be dynamic.

Kind regards,

> std::ofstream saveFile(fileName);
Use
std::ofstream saveFile( fileName.c_str() );