Visual Basic While Loop

In Visual Basic, While loop is useful to execute the block of statements as long as the specified condition is true.

 

In the previous section, we learned about for loop in visual basic with examples. Generally, the for loop is useful when we are sure about how many times we need to execute the block of statements. In case, if we are unknown about the number of times to execute the block of statements, then While loop is the best solution.

Visual Basic While Loop Syntax

Generally, we will use While keyword to create a while loop in Visual Basic applications. Following is the syntax of defining a while loop in Visual Basic programming language to execute the block of statements as long as the defined condition is true.

 

While boolean_expression

// Statements to Execute

End While

If you observe the above syntax, we used While keyword to define the while loop and it contains a parameter called boolean_expression.

 

Here, if boolean_expression returns true, then the statements inside of while loop will be executed. After executing the statements, again the boolean_expression will be evaluated to execute the statements within the While loop.

 

In case, the boolean_expression is evaluated to false, then the While loop stops the execution of statements and the program will come out of the loop.

Visual Basic While Loop Flow Chart

Following is the pictorial representation of While loop process flow in Visual Basic programming language.

 

Visual Basic While Loop Flow Chart Diagram

 

Now, we will see how to use While loop in Visual Basic programming language with examples.

Visual Basic While Loop Example

Following is the example of using While loop in Visual Basic programming language to execute the block of statements based on our requirements.

 

Module Module1

    Sub Main()

        Dim i As Integer = 1

        While i <= 4

            Console.WriteLine("i value: {0}", i)

            i += 1

        End While

        Console.WriteLine("Press Enter Key to Exit..")

        Console.ReadLine()

    End Sub

End Module

If you observe the above example, we are executing the statements within the While loop by checking the condition (i <= 4) and increasing the variable i (i++) value to 1 by using increment operator.

 

When we execute the above Visual Basic program, we will get the result like as shown below.

 

Visual Basic (VB) While Loop Example Result

 

If you observe the above result, While loop has executed till it matches the defined condition (i <= 4) and the program came out of the loop whenever the defined condition returns false.

Visual Basic Nested While Loop

In Visual Basic, we can use one While loop within another While loop to implement the applications based on our requirements.

 

Following is the example of implementing the nested While loop in Visual Basic programming language.

 

Module Module1

    Sub Main()

        Dim i As Integer = 1

        While i < 4

            Console.WriteLine("i value: {0}", i)

            i += 1

            Dim j As Integer = 1

            While j < 2

                Console.WriteLine("j value: {0}", j)

                j += 1

            End While

        End While

        Console.WriteLine("Press Enter Key to Exit..")

        Console.ReadLine()

    End Sub

End Module

If you observe above example, we used one While loop within another While loop to achieve the nested while loop functionality in our application based on our requirements.

 

When we execute the above Visual Basic program, we will get the result like as shown below.

 

i value: 1

j value: 1

i value: 2

j value: 1

i value: 3

j value: 1

Press Enter Key to Exit..

If you observe the above result, both While loops got executed and returned the result based on our requirements.

Visual Basic While Loop with Exit Statement

In Visual Basic, we can exit or terminate the execution of While loop immediately by using Exit keyword.

 

Following is the example of using Exit keyword in While loop to terminate the execution of loop in Visual Basic programming language.

 

Module Module1

    Sub Main()

        Dim i As Integer = 1

        While i < 4

            Console.WriteLine("i value: {0}", i)

            i += 1

            If i = 2 Then Exit While

        End While

        Console.WriteLine("Press Enter Key to Exit..")

        Console.ReadLine()

    End Sub

End Module

If you observe the above example, whenever the variable (i) value become 2 we are terminating the loop using Exit statement.

 

When we execute the above Visual Basic program, we will get the result like as shown below.

 

Visual Basic While Loop with Break Statement Example Result

 

This is how we can use the Exit statement with While loop to terminate the execution of loop based on our requirements.

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