Output error when input isn't a number. C++

Question

I am making a function that takes a number from the user\'s input and finds the absolute value of it. I want to make it return an error if the user inputs anything other than j

Answer 1

In addition to the great answers here, you could try using std::stringstream:

http://cplusplus.com/reference/iostream/stringstream/stringstream/

It works like any other stream for the most part, so you could do something like:

  int converted;
  string user_input;

  cin >> user_input;

  stringstream converter(user_input);


  if(!(converter >> converted)) {
    cout << "there was a problem converting the input." << endl;
  }
  else {
    cout << "input successfully converted: " << converted << endl;
  }

HTH!

P.S. personally, I would just use boost::lexical_cast<>, but for a homework assignment you probably won't have boost available to you. If you become a professional C++ programmer, Boost will become one of your best friends outside of the STL.