Here is a simple program in C++ to verify if a file exists using ifstream.

fexists.cpp

#include <iostream>
#include <fstream>

using namespace std;

bool fexists(const char *filename)
{
  ifstream ifile(filename);
  return ifile;
}

int main () {
  cout << fexists("filename") << endl;

  return 0;
}

Wrong. "ifile" is of type std::ifstream. The return type bool is incompatible.