Csharp/CSharp Tutorial/Statement/While

Compute integer powers of 2 with while loop

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);        
    } 
  }   
}

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

while(condition) statement;

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

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;
    }
  }
}

1 1 2 3 5 8 13 21 34

Use a while loop to display 1 to 5

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

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

Use count number to control while loop

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); 
  }   
}

Number: 435679
Magnitude: 6