Code Syntax Style: Implicit/Explicit Typing ('var' Keyword)

Press Control+Alt+S or choose File | Settings (Windows and Linux) or JetBrains Rider | Preferences (macOS) from the menu .

Go to the cleanup profiles settings page: Editor | Code Cleanup.

Create a new profile as described in the Create a new custom cleanup profile section. In the Selected profile settings section for the new profile, tick the Enforce 'var' keyword usage settings checkbox. Optionally, you can enable other code cleanup tasks in this profile.

Click Save in the Settings dialog to apply the modifications and let JetBrains Rider choose where to save them, or save the modifications to a specific settings layer using the Save To list. For more information, refer to layer-based settings.

Select the scope where you want to enforce your preferences:

• Place the caret anywhere in the file to enforce your preferences to the file.

• Select one or more items in the Solution Explorer to enforce your preferences in the files under these nodes and their child items.

Press Control+R, C or choose Code | Reformat and Cleanup… from the main menu .

In the Reformat and Cleanup Code dialog that opens, select the newly created profile and choose another scope if needed. .

Click OK. JetBrains Rider will enforce your preferences in the selected scope.

Press Control+K or select Git | Commit from the main menu.

In the Commit tool window, click and in the Commit Checks area, select the Cleanup with... checkbox.

Click Choose profile and choose your custom Code Cleanup profile.

Click Commit or Commit and Push. JetBrains Rider will run code cleanup in files staged for the commit, and then commit the changes.

Press Control+Alt+S to open the IDE settings and then select Tools | Actions on Save.

Select Reformat and Cleanup Code, choose your custom Code Cleanup profile and whether to apply it to the whole file or only to the changed lines.

The next time you finish editing and save the file or all files , JetBrains Rider will clean up the affected files using the selected profile.

Go to the Editor | Code Style | C# page of JetBrains Rider settings Control+Alt+S, and then select the Syntax Style tab .

Modify settings in the 'var' usage in declarations category according to your coding practices/standards.

You can set different preferences of using 'var' or explicit type for different types:

• For built-in types — applies to C# built-in types.

• For simple types — applies to types without generic parameters.

• Elsewhere — applies to generic types and deconstruction declarations.

For each of these preferences you can opt for using 'var', explicit type, or 'var' when evident.

If you have chosen Use 'var' when evident in the previous step, you can opt to apply Visual Studio logic to decide which cases should be considered evident.

To learn the differences between JetBrains Rider and Visual Studio logic, refer to Use 'var' when evident: what is considered evident?.

By default, JetBrains Rider will suggest joined notation for multiple var's in deconstruction declarations, for example var (x, y) = GetTuple();. You can select Prefer separate declarations for deconstructed variables to opt for separate notation, for example (var x, var y) = GetTuple();.

By default, JetBrains Rider suggests using standalone _ for discards, for example (_, _) = (0, 1);. You can select Use 'var' keyword for discards to always use var with discards where appropriate thus making sure that there are no conflicts with variables in the scope that may be named _.

The selectors in the right column allow you to set severity levels of code inspections detecting code that differs from your preferences.

Click Save in the Settings dialog to apply the modifications and let JetBrains Rider choose where to save them, or save the modifications to a specific settings layer using the Save To list. For more information, refer to layer-based settings.

Place the caret to a code issue highlighted by a JetBrains Rider's inspection.

Press Alt+Enter or click the action indicator to the left of the caret to open the action list.

In the action list, go to Inspection "Use preferred 'var' style" | Configure code style and then select a desired preference:

Your change will be saved using the smart save logic.

If you need to save the modified style preference in a shared settings layer, click the Configure code style menu item or press Enter when it is selected. JetBrains Rider will open the Editor | Code Style | C# | Syntax Style page of JetBrains Rider settings where you can modify your preference as needed, click Save To and then choose the desired settings layer.