Exit

In VB.NET programs, the Exit keyword breaks out of loops and Subs. It is followed by the name of the block we want to leave.

In a function, Exit While will stop the While-loop from iterating. And control flow will resume at the end of the loop.

Exit While

We use Exit in a While-loop. This program contains 4 Console.WriteLine statements. These help us locate the control flow as it proceeds through the statements.

Info Statement A is reached when the program begins. B is reached only once because the loop body is only entered once.

And C is not reached because the Exit While statement is first encountered. Statement D is reached after the Exit While statement is hit.

Module Module1
    Sub Main()
        Console.WriteLine("A")
        Dim i As Integer = 10

        While True
            Console.WriteLine("B")
            If i = 10 Then
                Exit While
            End If
            Console.WriteLine("C")
        End While

        Console.WriteLine("D")
    End Sub
End ModuleA
B
D

Exit `Sub`

In this next example, we see the Exit Sub statement. This statement breaks out of the entire Sub. This is the same as a Return statement.

Also Exit Sub is an alternative syntax to Return. If a While-loop contains an Exit While, the Exit Sub is more symmetric to this.

Module Module1
    Sub Main()
        Console.WriteLine("A")
        Dim i As Integer = 10

        While True
            Console.WriteLine("B")
            If i = 10 Then
                Exit Sub
            End If
            Console.WriteLine("C")
        End While

        Console.WriteLine("D")
    End Sub
End ModuleA
B

Discussion

In the C# language, a break statement exits from an enclosing loop. Break is the same as Exit. But in VB.NET Exit can be used instead of Return.

Also The Exit For statement does the same thing as the Exit While statement but acts upon a For-loop construct.

Tip These different statements are useful when nested. We can even Exit from a loop that is not immediately enclosing the statement.

Detail As with other loop Exit statements, Exit Do breaks out of an enclosing Do loop.

In VB.NET, we use Exit statements to stop procedural units from executing. This is simpler than attempting to set loop variables to an out-of-range value to cause loop termination.