== Why is this an issue?

Looking for a given substring starting from a specified offset can be achieved by such code: ``++str.Substring(startIndex).IndexOf(char1)++``. This works well, but it creates a new ``++string++`` for each call to the ``++Substring++`` method. When this is done in a loop, a lot of ``++strings++`` are created for nothing, which can lead to performance problems if ``++str++`` is large.


To avoid performance problems, ``++string.Substring(startIndex)++`` should not be chained with the following methods:

* ``++IndexOf++``
* ``++IndexOfAny++``
* ``++LastIndexOf++``
* ``++LastIndexOfAny++``

For each of these methods, another method with an additional parameter is available to specify an offset.

Using these methods gives the same result while avoiding the creation of additional ``++String++`` instances.

=== Noncompliant code example

[source,csharp]
----
str.Substring(StartIndex).IndexOf(char1); // Noncompliant; a new string is going to be created by "Substring"
----

=== Compliant solution

[source,csharp]
----
str.IndexOf(char1, startIndex) - startIndex;
----

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