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
str.Substring(StartIndex).IndexOf(char1); // Noncompliant; a new string is going to be created by "Substring"
Compliant solution
str.IndexOf(char1, startIndex) - startIndex;
