Question

I have some text files in a folder named foo1, foo2,…,foo5. I tried to write a C++ program
to print out the contents of the files but the compiler is giving an error.
Here is the program.

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

  string common="foo";

  for(int count=1;count<=5;++count)
  {
  //Convert count to an string.
  stringstream ss;
  ss<<count;
  string numstring=ss.str();

  string filename=common+numstring;
  ifstream infile(filename); 
  string line;

  //Print out the lines from the file.
   while(getline(infile,line))
     {
       cout<<line<<endl;

     }
  }

  return 0;
}

The compiler is giving an error like

g++ -Wall c++.cpp
c++.cpp: In function ‘int main(int, char**)’:
c++.cpp:26: error: no matching function for call to ‘std::basic_ifstream<char, std::char_traits<char> >::basic_ifstream(std::string&)’
/usr/include/c++/4.4/fstream:454: note: candidates are: std::basic_ifstream<_CharT, _Traits>::basic_ifstream(const char*, std::_Ios_Openmode) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.4/fstream:440: note:                 std::basic_ifstream<_CharT, _Traits>::basic_ifstream() [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.4/iosfwd:81: note:                 std::basic_ifstream<char, std::char_traits<char> >::basic_ifstream(const std::basic_ifstream<char, std::char_traits<char> >&)

Can someone help me out with this? The output of the program should be what I would get if I typed cat foo* at the terminal.

Answer 1

Replace:

ifstream infile(filename);

with

ifstream infile(filename.c_str());

The error message that you posted shows you this. fstream is a typedef for basic_fstream<>. Your error message says, in essence, that there is no fstream constructor that takes a string&, but there is one that takes a char*.