VB.NET While End Loop

The While End loop is used to execute blocks of code or statements in a program, as long as the given condition is true. It is useful when the number of executions of a block is not known. It is also known as an entry-controlled loop statement, which means it initially checks all loop conditions. If the condition is true, the body of the while loop is executed. This process of repeated execution of the body continues until the condition is not false. And if the condition is false, control is transferred out of the loop.

Syntax:

While [condition]
	[ Statement to be executed ]
End While

Here, condition represents any Boolean condition, and if the logical condition is true, the single or block of statements define inside the body of the while loop is executed.

Flow Diagram of the While End Loop in VB.NET

As we know, the While End loop is an entry-controlled loop used to determine if the condition is true, the statements defined in the body of the loop are executed, and the execution process continues till the condition is satisfied. Furthermore, after each iteration, the value of the counter variable is incremented. It again checks whether the defined condition is true; And if the condition is again true, the body of the While loop is executed. And when the condition is not true, the control transferred to the end of the loop.

Example: Write a simple program to print the number from 1 to 10 using while End loop in VB.NET.

while_number.vb

Imports System
Module while_number
    Sub Main()
        'declare x as an integer variable
        Dim x As Integer
        x = 1
        ' Use While End condition
        While x <= 10
            'If the condition is true, the statement will be executed.
            Console.WriteLine(" Number {0}", x)
            x = x + 1 ' Statement that change the value of the condition
        End While
        Console.WriteLine(" Press any key to exit...")
        Console.ReadKey()
    End Sub
End Module

Output:

In the above example, while loop executes its body or statement up to the defined state (i <= 10). And when the value of the variable i is 11, the defined condition will be false; the loop will be terminated.

Example 2: Write a program to print the sum of digits of any number using while End loop in VB.NET.

Total_Sum.vb

Public Class Total_Sum ' Create a Class Total_sum
    Shared Sub Main()
        'Declare an Integer variable
        Dim n, remainder, sum As Integer
        sum = 0

        Console.WriteLine(" Enter the number :")
        n = Console.ReadLine()  ' Accept a number from the user

        ' Use While loop and write given below condition  
        While (n > 0)
            remainder = n Mod 10
            sum += remainder
            n = n / 10
        End While
        Console.WriteLine(" Sum of digit is :{0}", sum)
        Console.WriteLine(" Press any key to exit...")
        Console.ReadKey()
    End Sub
End Class

Output:

Nested While End Loop

In VB.NET, when we write a While End loop inside the body of another While End loop, it is called Nested While End loop.

Syntax

While (condition -1)
// body of the outer while loop
While (condition -2)
                     // body of inner while loop
End While
// body of the outer loop
End While

Write a program to understand the Nested While End loop in VB.NET programming.

Nest_While.vb

Imports System
Module Nest_While
    Sub Main()
        ' Declare i and j as Integer variable
        Dim i As Integer = 1


        While i < 4
            ' Outer loop statement
            Console.WriteLine(" Counter value of Outer loop is {0}", i)
            Dim j As Integer = 1

            While j < 3
                'Inner loop statement
                Console.WriteLine(" Counter value of Inner loop is {0}", j)
                j = j + 1 ' Increment Inner Counter variable by 1
            End While
            Console.WriteLine() 'print space
            i = i + 1   ' Increment Outer Counter variable by 1
        End While
        Console.WriteLine(" Press any key to exit...")
        Console.ReadKey()
    End Sub
End Module

Output:

In the above example, at each iteration of the outer loop, the inner loop is repeatedly executed its entire cycles until the inner condition is not satisfied. And when the condition of the outer loop is false, the execution of the outer and inner loop is terminated.

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