Exceptional C++ Style 40 New Engineering Puzzles, Programming Problems, and Solutions

Chapter 30. double or Nothing

Difficulty: 4

No, this Item isn't about gambling. It is, however, about a different kind of “float,” so to speak, and lets you test your skills about basic floating-point operations in C and C++.

JG Question

1. What's the difference between float and double?

Guru Question

1. Say that the following program takes 1 second to run, which is not unusual for a modern desktop computer:

   int main() {
     double x = 1e8;
     while(x > 0) {
      --x;
     }
   }
   

How long would you expect it to take if you changed double to float? Why?

Solution

float and double in a Nutshell

1. What's the difference between float and double?

Quoting from the C++ standard:

There are three floating point types: float, double, and long double. The type double provides at least as much ...