Restricting data types?

Hi,

I'm new to programming and need some help with a program i wrote.

I have written the program as follows:

Code:

---

#include <iostream>

using namespace std;

double ftoc ( double f );

int main()
{
    double f; double c;

    for ( int y = 1; y != 0 && y == 1; y )
    {
    cout<<"Enter degrees in Fahrenheit: ";
    cin>> f;
    cin.ignore();

    cout<< f <<" degrees Fahrenheit is "<< ftoc ( f ) <<" degrees Celsius\n\n";

    cout<<"Do you want to convert again (yes = 1,no = 0): ";
    cin>> y;
    cin.ignore();
    while ( y != 1 && y != 0 )
      {
      cout<<"You need to enter either a 1 or 0\n\n";
      cout<<"Do you want to convert again (yes = 1,no = 0): ";
      cin>> y;
      cin.ignore();
      }
    cout<<"\n";
    }
}

double ftoc ( double f )
{
    return (5.0/9.0)* (f - 32.0);
}

---

I noticed that when my program asks to enter in the degrees fahrenheit, if you enter in anything other than a number it goes into an infinite loop. Now, I want to protect against this by adding a loop asking to enter a number, but how do I go about doing this? I assume you would have to restrict data types, but I'm not sure how that is done.

Also another question I have is if its possible to insert a degree symbol in the program? If so, then how do you insert it?
Any help is appreciated.

Thanks

Code:

---

double f;
while (!(cin >> f))
{
  cin.clear();
  cin.ignore(1000, '\n');
  // Prompt about the bad input and ask for input again.
}

---

If you also want to error out when the user types some good input followed by bad input (e.g. "76.4 is the answer\n"), then this code will do that:

Code:

---

double f;
while (!(cin >> f) || cin.get() != '\n')
{
  cin.clear();
  cin.ignore(1000, '\n');
  // Prompt about the bad input and ask for input again.
}

---

>> possible to insert a degree symbol in the program?
Perhaps:

Code:

---

cout << 'º'; // alt-167

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