Appendix E

Control Statements

Control statements tell an application which other statements to execute under a particular set of circumstances.

The two main categories of control statements are decision statements and looping statements. The following sections describe the decision and looping statements provided by Visual Basic .NET.


A decision statement represents a branch in the program. It marks a place where the program can execute one set of statements or another or possibly no statements at all. These include If, Choose, and Select Case statements.

Single-Line If Then

A single-line If Then statement tests a condition and, if the condition is true, executes a piece of code. The code may include more than one simple statement separated by a colon.

Optional Else If clauses let the program evaluate other conditions and execute corresponding pieces of code. A final optional Else clause lets the program execute a piece of code if none of the previous conditions is true.

The syntax for different variations are as follows:

If condition Then statement
If condition Then statement1 Else statement2
If condition1 Then statement1 Else If condition2 Then statement2 _
    Else statement3
If condition Then statement1: statement2
If condition Then statement1: statement2 Else statement3: statement4

Complicated single-line If Then statements can be confusing and difficult to read, so I recommend using the multiline versions if the statement includes an Else clause or executes ...

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