Use index operator (IDE0056)

Property	Value
Rule ID	IDE0056
Title	Use index operator
Category	Style
Subcategory	Language rules (expression-level preferences)
Applicable languages	C# 8.0+
Options	csharp_style_prefer_index_operator

Overview

This style rule concerns the use of the index-from-end operator (^), which is available in C# 8.0 and later.

Options

Options specify the behavior that you want the rule to enforce. For information about configuring options, see Option format.

csharp_style_prefer_index_operator

Property	Value	Description
Option name	csharp_style_prefer_index_operator
Option values	true	Prefer to use the ^ operator when calculating an index from the end of a collection
	false	Prefer not to use the ^ operator when calculating an index from the end of a collection
Default option value	true

// csharp_style_prefer_index_operator = true
string[] names = { "Archimedes", "Pythagoras", "Euclid" };
var index = names[^1];

// csharp_style_prefer_index_operator = false
string[] names = { "Archimedes", "Pythagoras", "Euclid" };
var index = names[names.Length - 1];

Suppress a warning

If you want to suppress only a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable IDE0056
// The code that's violating the rule is on this line.
#pragma warning restore IDE0056

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.IDE0056.severity = none

To disable all of the code-style rules, set the severity for the category Style to none in the configuration file.

[*.{cs,vb}]
dotnet_analyzer_diagnostic.category-Style.severity = none

For more information, see How to suppress code analysis warnings.

See also

• index-from-end operator
• Code style language rules
• Code style rules reference