Add explicit cast in foreach loop (IDE0220)
| Property | Value |
|---|---|
| Rule ID | IDE0220 |
| Title | Add explicit cast |
| Category | Style |
| Subcategory | Language rules (expression-level preferences) |
| Applicable languages | C# |
| Options | dotnet_style_prefer_foreach_explicit_cast_in_source |
Overview
This rule flags the absence of an explicit cast in a foreach loop when the compiler would add a hidden cast. For generic, or strongly typed, collections, forcing an explicit cast when the compiler would add a hidden cast can uncover the use of an incorrect type in the foreach statement.
Options
Options specify the behavior that you want the rule to enforce. For information about configuring options, see Option format.
dotnet_style_prefer_foreach_explicit_cast_in_source
| Property | Value | Description |
|---|---|---|
| Option name | dotnet_style_prefer_foreach_explicit_cast_in_source | |
| Option values | always |
Prefer explicit casts in source code. |
when_strongly_typed |
Prefer explicit casts for strongly typed (generic) collections but not for legacy collections, such as ArrayList. | |
| Default option value | when_strongly_typed |
Example
// Code with violations.
var list = new List<object>();
foreach (string item in list) { }
// Fixed code.
var list = new List<object>();
foreach (string item in list.Cast<string>())
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 IDE0220
// The code that's violating the rule is on this line.
#pragma warning restore IDE0220
To disable the rule for a file, folder, or project, set its severity to none in the configuration file.
[*.{cs,vb}]
dotnet_diagnostic.IDE0220.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.
