How to Compare Files in Visual Studio

Comparing files to identify differences is a crucial task for developers. Visual Studio provides robust built-in tools for file comparison, allowing you to visually inspect changes side-by-side or inline. This comprehensive guide will show you how to compare files effectively within Visual Studio, both through the IDE and the command line.

Comparing Files Using the Visual Studio IDE

Visual Studio offers multiple ways to compare files directly within the IDE:

Comparing Selected Files

In Solution Explorer, select the two files you want to compare. You can use Ctrl + click to select multiple files.
Right-click on one of the selected files.
Choose Compare Selected from the context menu. This opens the diff view, displaying the differences between the two files.

Comparing with a Specific File

Right-click on the file you want to compare.
Select Compare With… from the context menu. This will open the Open File dialog.
Navigate to and select the second file you want to compare. The second file doesn’t need to be part of your current solution.
Click Open. The diff view will appear, with the right-clicked file considered the newer version (editable) and the selected file as the older version (read-only).

Comparing Files via the Command Line

You can also compare files using the Visual Studio Developer Command Prompt:

Open the Developer Command Prompt.
Use the /Diff (or -diff) command with the following syntax:

devenv /Diff SourceFile TargetFile [SourceDisplayName [TargetDisplayName]]

Replace SourceFile and TargetFile with the paths to your files. SourceDisplayName and TargetDisplayName are optional and allow you to customize the file names displayed in the comparison view. Visual Studio will open and display the files side-by-side, with TargetFile as the editable newer version.

Understanding the Differences

Visual Studio highlights differences with clear visual cues:

(-) Minus Sign: Indicates lines removed from the newer version.
(+) Plus Sign: Indicates lines added to the newer version.
Red and Green Boxes: Highlight specific text changes within a line. Red represents the old version, while green represents the new version.

Navigation arrows at the top left corner of the diff view allow you to jump between changes. You can also switch between two different view modes:

Side-by-Side View: Displays the files in a split-screen format.
Inline View: Shows the differences within a single window.

Customizing Display Settings in the Diff View

Visual Studio allows customizing the diff view with various settings accessed through the gear icon:

Setting	Keyboard Shortcut	Description
Summary	`Ctrl` + , `Ctrl` + `5`	Toggles display of only differing parts or the entire files.
Inline Mode	`Ctrl` + , `Ctrl` + `1`	Displays differences within a single file view.
Side-by-Side Mode	`Ctrl` + , `Ctrl` + `2`	Displays files in a split-screen view.
Left File Only	`Ctrl` + , `Ctrl` + `3`	Displays only the left file (the one selected in the “Open File” dialog).
Right File Only	`Ctrl` + , `Ctrl` + `4`	Displays only the right file (the one right-clicked on).
Ignore Trim Whitespace	`Ctrl` + , `Ctrl` + `Space`	Ignores trailing whitespace differences at the end of lines.
Synchronize Views	`Ctrl` + , `Ctrl` + `Down Arrow`	Locks scrollbars together for simultaneous scrolling of both files.

Utilizing these features and techniques, you can efficiently compare files within Visual Studio, streamline your workflow, and improve code quality.