std::basic_ios<CharT,Traits>::fail (3) - Linux Manuals

std::basic_ios<CharT,Traits>::fail: std::basic_ios<CharT,Traits>::fail

NAME

std::basic_ios<CharT,Traits>::fail - std::basic_ios<CharT,Traits>::fail

Synopsis

bool fail() const;

Returns true if an error has occurred on the associated stream. Specifically, returns true if badbit or failbit is set in rdstate().
See ios_base::iostate for the list of conditions that set failbit or badbit.

Parameters

(none)

Return value

true if an error has occurred, false otherwise.

Example

// Run this code

  #include <iostream>
  #include <fstream>
  #include <cstdlib>
  int main()
  {
      std::ifstream file("test.txt");
      if(!file) // operator! is used here
      {
          std::cout << "File opening failed\n";
          return EXIT_FAILURE;
      }

      // typical C++ I/O loop uses the return value of the I/O function
      // as the loop controlling condition, operator bool() is used here
      for(int n; file >> n; ) {
         std::cout << n << ' ';
      }
      std::cout << '\n';

      if (file.bad())
          std::cout << "I/O error while reading\n";
      else if (file.eof())
          std::cout << "End of file reached successfully\n";
      else if (file.fail())
          std::cout << "Non-integer data encountered\n";
  }