C++ isdigit command

[Scoody]

How about this function then?

Code: Select all

// Asks the user from a number, and keeps asking until it gets a valid one
int getNumber() 
{
  int intval = 0;
  while (true) {
    cout << "Number please: ";
    cin >> intval;
    if (cin.fail()) {
      cout << "Something bad happened ..." << endl;
      cin.clear(); // clear the failstate
      cin.sync(); // clear cin's buffer of nastiness
    } else {
      // since cin didn't fail, it must be a valid number
      return intval;
    }
  }
}

[herby490]

No that did not work either. Cin still fails when I enter something like 3gsad.

[Scoody]

That's weird, it works fine here. It even returns 3 when I feed it "3gsad". So it seems the >> operator extracts the numbers until it encounters a non-number.
You could try using this "hack" instead of cin.sync(), if it's an implementation issue or something..

Code: Select all

cin.ignore(cin.rdbuf()->in_avail());

[herby490]

I guess my problem is that the compiler thinks that the number/letter combination is a number so its not failing the cin.

[herby490]

Do you think the fact that your using ints and i am using doubles has anything to do with it?

[MarauderIIC]

Try changing it to int and find out? :)

[herby490]

Try changing it to int and find out?

No it does not work. Man this is getting annoying.

[Maevik]

Maevik, !cin is shorthand for cin.fail() (or !cin.good(), perhaps)

Good to know, thx.

[Scoody]

How about this one?
You may have to include <cstdlib> for atof().

Code: Select all

double getNumber() 
{
  char numstr[65];
  cin.getline(numstr,65);
  return atof(numstr);
}