== Why is this an issue?

A chain of https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/statements/selection-statements#the-if-statement[if/else if] 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,csharp,diff-id=1,diff-type=noncompliant]
----
if (param == 1)
{
  OpenWindow();
}
else if (param == 2)
{
  CloseWindow();
}
else if (param == 1) // Noncompliant: condition has already been checked
{
  MoveWindowToTheBackground(); // unreachable code
}
----

==== Compliant solution

[source,csharp,diff-id=1,diff-type=compliant]
----
if (param == 1)
{
  OpenWindow();
}
else if (param == 2)
{
  CloseWindow();
}
else if (param == 3)
{
  MoveWindowToTheBackground();
}
----

== Resources

=== Documentation

* https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/statements/selection-statements#the-if-statement[The if statement]


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

'''
== 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)

=== on 25 Mar 2015, 16:03:23 Tamas Vajk wrote:
\[~ann.campbell.2] should I add the See section for C# as well?

=== on 25 Mar 2015, 16:24:48 Ann Campbell wrote:
\[~tamas.vajk] these language-specific subtasks override portions of their parent tasks, and the description field is treated as 5 separate parts: description, Noncompliant Code Example, Compliant Solution, Exceptions, and references (See). There's no need to copy/paste the references to this child ticket, but do include them in the implementation's rule description.

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

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