// FILE: ToDigit.cpp

#include <ctype.h>	// for isdigit ()

// DETERMINES THE EQUIVALENT INTEGER FORM OF ITS CHARACTER INPUT
bool to_digit
  (char ch,			// IN: the character to be converted
   int& i)			// OUT: the integer form of ch (or -1)
// Pre : ch must be a digit character.
// Post: converts ch to a decimal digit
// Returns: true if ch is a digit character and false otherwise.
//          Also returns through the output argument i the
//          integer form of the character input argument
//          (or -1 if this character is not a digit).

{
   // Determine if ch is a digit character.
   if (isdigit (ch))
   {
      i = int (ch) - int ('0');
      return true;
   }
   else
   {
      i = -1;
      return false;
   }
}  // end to_digit