== Why is this an issue?

A chain of https://learn.microsoft.com/en-us/dotnet/visual-basic/language-reference/statements/if-then-else-statement[If/ElseIf] statements is evaluated from top to bottom. At most, only one branch will be executed: the first statement with a condition that evaluates to `True`. 
Therefore, duplicating a condition leads to unreachable code inside the duplicated condition block. Usually, this is due to a copy/paste error. 

The result of such duplication can lead to unreachable code or even to unexpected behavior.

== How to fix it

=== Code examples

==== Noncompliant code example

[source,vbnet,diff-id=1,diff-type=noncompliant]
----
If param = 1 Then
  OpenWindow()
ElseIf param = 2 Then
  CloseWindow()
ElseIf param = 1 Then ' Noncompliant: condition has already been checked
  MoveWindowToTheBackground() ' unreachable code
End If
----

==== Compliant solution

[source,vbnet,diff-id=1,diff-type=compliant]
----
If param = 1 Then
  OpenWindow()
ElseIf param = 2 Then
  CloseWindow()
ElseIf param = 3 Then
  MoveWindowToTheBackground()
End If
----

== Resources

=== Documentation

* https://learn.microsoft.com/en-us/dotnet/visual-basic/language-reference/statements/if-then-else-statement[If...Then...Else Statement]

ifdef::env-github,rspecator-view,env-vscode[]

'''
== Implementation Specification
(visible only on this page)

=== Message

This branch duplicates the one on line n.

include::../highlighting.adoc[]

'''
== Comments And Links
(visible only on this page)

include::../comments-and-links.adoc[]

endif::env-github,rspecator-view,env-vscode[]