Csharp/CSharp Tutorial/Statement/While

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Compute integer powers of 2 with while loop

<source lang="csharp">using System;

class MainClass {

 public static void Main() { 
   int e; 
   int result; 

   for(int i=0; i < 10; i++) { 
     result = 1; 
     e = i; 

     while(e > 0) { 
       result *= 2; 
       e--; 
     } 

     Console.WriteLine("2 to the " + i + " power is " + result);        
   } 
 }   

}</source>

2 to the 0 power is 1
2 to the 1 power is 2
2 to the 2 power is 4
2 to the 3 power is 8
2 to the 4 power is 16
2 to the 5 power is 32
2 to the 6 power is 64
2 to the 7 power is 128
2 to the 8 power is 256
2 to the 9 power is 512

Simplest While loop

The general form of the while loop is


<source lang="csharp">while(condition) statement;</source>

Use a while loop to calculate and display the Fibonacci numbers less than 50

<source lang="csharp">class MainClass {

 public static void Main()
 {
   int oldNumber = 1;
   int currentNumber = 1;
   int nextNumber;
   System.Console.Write(currentNumber + " ");
   while (currentNumber < 50)
   {
     System.Console.Write(currentNumber + " ");
     nextNumber = currentNumber + oldNumber;
     oldNumber = currentNumber;
     currentNumber = nextNumber;
   }
 }

}</source>

1 1 2 3 5 8 13 21 34

Use a while loop to display 1 to 5

<source lang="csharp">class MainClass {

 public static void Main()
 {
   int counter = 1;
   while (counter <= 5)
   {
     System.Console.WriteLine("counter = " + counter);
     counter++;
   }
 }

}</source>

counter = 1
counter = 2
counter = 3
counter = 4
counter = 5

Use count number to control while loop

<source lang="csharp">using System;

class MainClass {

 public static void Main() { 
   int num; 
   int mag; 

   num = 435679; 
   mag = 0; 

   Console.WriteLine("Number: " + num); 

   while(num > 0) { 
     mag++; 
     num = num / 10; 
   }; 

   Console.WriteLine("Magnitude: " + mag); 
 }   

}</source>

Number: 435679
Magnitude: 6