== Why is this an issue?

Most checks against an ``++IndexOf++`` value compare it with -1 because 0 is a valid index. Any checks which look for values ``++> 0++`` ignore the first element, which is likely a bug. If the intent is merely to check inclusion of a value in a ``++string++``, ``++List++``, or an array, consider using the ``++Contains++`` method instead.


This rule raises an issue when an ``++IndexOf++`` value retrieved from a ``++string++``, ``++List++`` or array is tested against ``++> 0++``.

This rule also raises an issue when ``++IndexOfAny++``, ``++LastIndexOf++`` or ``++LastIndexOfAny++`` from a ``++string++`` is tested against ``++> 0++``

=== Noncompliant code example

[source,csharp]
----
string color = "blue";
string name = "ishmael";

List<string> strings = new List<string>();
strings.Add(color);
strings.Add(name);
string[] stringArray = strings.ToArray();

if (strings.IndexOf(color) > 0) // Noncompliant
{  
  // ...
}

if (name.IndexOf("ish") > 0) // Noncompliant
{ 
  // ...
}

if (name.IndexOf("ae") > 0) // Noncompliant
{ 
  // ...
}

if (Array.IndexOf(stringArray, color) > 0) // Noncompliant
{  
  // ...
}
----

=== Compliant solution

[source,csharp]
----
string color = "blue";
string name = "ishmael";

List<string> strings = new List<string> ();
strings.Add(color);
strings.Add(name);
string[] stringArray = strings.ToArray();

if (strings.IndexOf(color) > -1) 
{
  // ...
}

if (name.IndexOf("ish") >= 0) 
{
  // ...
}

if (name.Contains("ae"))
{
  // ...
}

if (Array.IndexOf(stringArray, color) >= 0)
{  
  // ...
}
----

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

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

include::../message.adoc[]

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

include::comments-and-links.adoc[]
endif::env-github,rspecator-view[]