Csharp/C Sharp/Data Types/double

Compute the area of a circle

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Compute the area of a circle. 
  
using System;  
   
public class ComputeCircle {   
  static void Main() {   
    double radius; 
    double area; 
 
    radius = 10.0; 
    area = radius * radius * 3.1416; 
 
    Console.WriteLine("Area is " + area); 
  }   
}

converts Fahrenheit to Celsius

/*  
   This program converts Fahrenheit to Celsius. 
 
   Call this program FtoC.cs. 
*/ 
 
using System; 
  
public class FtoC {  
  public static void Main() {  
    double f; // holds the temperature in Fahrenheit 
    double c; // holds the temparture in Celsius 
 
    f = 59.0; // start with 59 degrees Fahrenheit 
 
    c = 5.0 / 9.0 * (f - 32.0); // convert to Celsius 
 
    Console.Write(f + " degrees Fahrenheit is "); 
    Console.WriteLine(c + " degrees Celsius."); 
  }  
}

double number format: 0:C, 0:D9, 0:E, 0:F3, 0:N, 0:X, 0:x

 
using System;
using System.Collections.Generic;
using System.Text;
class Program {
    static void Main(string[] args) {
        Console.WriteLine("C format: {0:C}", 99989.987);
        Console.WriteLine("D9 format: {0:D9}", 99999);
        Console.WriteLine("E format: {0:E}", 99999.76543);
        Console.WriteLine("F3 format: {0:F3}", 99999.9999);
        Console.WriteLine("N format: {0:N}", 99999);
        Console.WriteLine("X format: {0:X}", 99999);
        Console.WriteLine("x format: {0:x}", 99999);
    }
}

Epsilon, PositiveInfinity, NegativeInfinity, MaxValue, MinValue

 
using System;
using System.Collections.Generic;
using System.Text;
class Program {
    static void Main(string[] args) {
        Console.WriteLine("-> double.Epsilon: {0}", double.Epsilon);
        Console.WriteLine("-> double.PositiveInfinity: {0}", double.PositiveInfinity);
        Console.WriteLine("-> double.NegativeInfinity: {0}", double.NegativeInfinity);
        Console.WriteLine("-> double.MaxValue: {0}", double.MaxValue);
        Console.WriteLine("-> double.MinValue: {0}", double.MinValue);
    }
}

Format double value

 
using System;
public class NumParsingApp
{
    public static void Main(string[] args)
    {
        int i = int.Parse("12345");
        Console.WriteLine("i = {0}", i);
   
        int j = Int32.Parse("12345");
        Console.WriteLine("j = {0}", j);
   
        double d = Double.Parse("1.2345E+6");
        Console.WriteLine("d = {0:F}", d);
   
        string s = i.ToString();
        Console.WriteLine("s = {0}", s);
    }
}

Implement the Pythagorean Theorem

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Implement the Pythagorean Theorem. 
  
using System;  
  
public class Pythagorean {     
  public static void Main() {     
    double s1; 
    double s2; 
    double hypot; 
    string str; 
 
    Console.WriteLine("Enter length of first side: "); 
    str = Console.ReadLine(); 
    s1 = Double.Parse(str); 
 
    Console.WriteLine("Enter length of second side: "); 
    str = Console.ReadLine(); 
    s2 = Double.Parse(str); 
 
    hypot = Math.Sqrt(s1*s1 + s2*s2); 
  
    Console.WriteLine("Hypotenuse is " + hypot); 
  }     
}

Talking to Mars: double value calculation

/*
C# A Beginner"s Guide
By Schildt
Publisher: Osborne McGraw-Hill
ISBN: 0072133295
*/
/* 
   Project 2-1 
 
   Talking to Mars 
 
   Call this file mars.cs 
*/ 
 
using System; 
 
public class Mars {    
  public static void Main() {    
    double distance; 
    double lightspeed; 
    double delay; 
    double delay_in_min; 
 
    distance = 34000000; // 34,000,000 miles 
    lightspeed = 186000; // 186,000 per second 
 
    delay = distance / lightspeed;     
 
    Console.WriteLine("Time delay when talking to Mars: " + 
                      delay + " seconds."); 
     
    delay_in_min = delay / 60; 
 
    Console.WriteLine("This is " + delay_in_min + 
                      " minutes."); 
  }    
}

the differences between int and double

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
/*  
   This program illustrates the differences 
   between int and double. 
*/  
 
using System; 
 
public class Example3IntDouble {  
  public static void Main() {  
    int ivar;     // this declares an int variable 
    double dvar;  // this declares a floating-point variable 
 
    ivar = 100;   // assign ivar the value 100 
    
    dvar = 100.0; // assign dvar the value 100.0 
 
    Console.WriteLine("Original value of ivar: " + ivar); 
    Console.WriteLine("Original value of dvar: " + dvar); 
 
    Console.WriteLine(); // print a blank line 
 
    // now, divide both by 3 
    ivar = ivar / 3;  
    dvar = dvar / 3.0; 
 
    Console.WriteLine("ivar after division: " + ivar); 
    Console.WriteLine("dvar after division: " + dvar); 
  }  
}