// while.cxx
#include <iostream>
#include <cstdlib>
#include <cctype>  // needed to use isdigit() etc.

using std::cout;
using std::cin;
using std::endl;

int main()
{
   char readchar;
   int numeral, number = 0;

   cout << "Program to read integers safely:" << endl;
   cout << "Enter an integer" << endl;

   // STRIP OUT ALL LEADING NON-DIGIT CHARACTERS
   // Read and discard characters as long as they are not digits
   readchar = cin.get();
   while( !isdigit( readchar ) )
      readchar = cin.get();

   // READ THE DIGITS, CONSTRUCT THE INTEGER
   // Read characters as long as they are digits/numerals
   while( isdigit(readchar) )
   {
       // Convert the read character to a numeral
       numeral = readchar - '0';

       // To make the new numeral the units digit,
       //   multiply current integer by 10 and add new numeral to it
       number = number * 10 + numeral;
       readchar = cin.get();
   }

   // Print the constructed integer
   cout << number << endl;

   return EXIT_SUCCESS;
}