Floating Point Types

1. Replacing float with double produces an outcome that is surprising in a different way:

   // ...
   
       double result = 0;
   
   // ...
   
       if (result == 1) {
           writeln("As expected: 1");
   
       } else {
           writeln("DIFFERENT: ", result);
       }
   

   Although the value fails the result == 1 comparison, it is still printed as 1:

   DIFFERENT: 1
   

   That surprising outcome is related to the way floating point values are formatted for printing. A more accurate approximation of the value can be seen when the value is printed with more digits after the decimal point. (We will see formatted output in a later chapter.):

           writefln("DIFFERENT: %.20f", result);
   

   DIFFERENT: 1.00000000000000066613
   

2. Replacing the three ints with three doubles is sufficient:

           double first;
           double second;
   
           // ...
   
           double result;
   

3. The following program demonstrates how much more complicated it would become if more than five variables were needed:

   import std.stdio;
   
   void main() {
       double value_1;
       double value_2;
       double value_3;
       double value_4;
       double value_5;
   
       write("Value 1: ");
       readf(" %s", &value_1);
       write("Value 2: ");
       readf(" %s", &value_2);
       write("Value 3: ");
       readf(" %s", &value_3);
       write("Value 4: ");
       readf(" %s", &value_4);
       write("Value 5: ");
       readf(" %s", &value_5);
   
       writeln("Twice the values:");
       writeln(value_1 * 2);
       writeln(value_2 * 2);
       writeln(value_3 * 2);
       writeln(value_4 * 2);
       writeln(value_5 * 2);
   
       writeln("One fifth the values:");
       writeln(value_1 / 5);
       writeln(value_2 / 5);
       writeln(value_3 / 5);
       writeln(value_4 / 5);
       writeln(value_5 / 5);
   }