Use switch expression (IDE0066)

Property	Value
Rule ID	IDE0066
Title	Use switch expression
Category	Style
Subcategory	Language rules (pattern matching preferences)
Applicable languages	C# 8.0+
Introduced version	Visual Studio 2019
Options	csharp_style_prefer_switch_expression

Overview

This style rule concerns the use of switch expressions, which were introduced in C# 8.0, versus switch statements.

Options

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

csharp_style_prefer_switch_expression

Property	Value	Description
Option name	csharp_style_prefer_switch_expression
Option values	true	Prefer to use a switch expression
	false	Prefer to use a switch statement
Default option value	true

// csharp_style_prefer_switch_expression = true
return x switch
{
    1 => 1 * 1,
    2 => 2 * 2,
    _ => 0,
};

// csharp_style_prefer_switch_expression = false
switch (x)
{
    case 1:
        return 1 * 1;
    case 2:
        return 2 * 2;
    default:
        return 0;
}

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 IDE0066
// The code that's violating the rule is on this line.
#pragma warning restore IDE0066

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

[*.{cs,vb}]
dotnet_diagnostic.IDE0066.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

• switch expression
• Code style language rules
• Code style rules reference