// function to convert char strings of numbers to integers

int string_to_integer(char string[])
{
   int i, integer_val, result = 0;
   for (i=0; string[i] >= '0' && string[i] <= '9'; ++i) // read the string
      { integer_val = string[i] - '0';     // do the conversion       
        result = result * 10 + integer_val;
      }
   return (result);
}