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``.

== Noncompliant Code Example

----
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

----
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)
{  
  // ...
}
----