# Making Calculations

*Part of* TutorialFundamentals

This program demonstrates getting input from the console window, making a simple calculation, and returing the output.

/* Purpose: Calculate the area of a circle Author: J C Calvarese License: Public Domain */ import std.c.stdio; /* for scanf */ import std.stdio; /* for writef/writefln */ const double pi = 3.141592654; void main() { writefln("Let's calculate the area of a circle."); writef("What is the radius? "); double radius; scanf("%lf", &radius); double area; area = pi * radius * radius; writefln("Area: %s", area); }

When you run it, the console screen should look something like this (if you provide a radius of 5):

Let's calculate the area of a circle. What is the radius? 5 Area: 78.5398