Read and understand C++ code in Visual Studio

Grein
09/27/2022

The C++ code editor and Visual Studio IDE provide many coding aids. Some are unique to C++, and some are essentially the same for all Visual Studio languages. For more information about the shared features, see Writing Code in the Code and Text Editor.

Colorization

Visual Studio colorizes syntax elements to differentiate between types of symbols such as language keywords, type names, variable names, function parameters, string literals, and so on.

Screenshot showing code colorization in the editor. Keywords are shown in different colors such as blue for if, while and green for comments

Unused code (such as code under an #if 0) is more faded in color.

Screenshot showing inactive code in the editor, which appears faded compared to active code.

You can customize the colors by typing "Fonts" in Quick Launch, and then choosing Fonts and Colors. In the Fonts and Colors dialog, scroll down to the C/C++ options and then choose a custom font and/or color.

Outlining

Right-click anywhere in a source code file and choose Outlining to collapse or expand code blocks and/or custom regions to make it easier to browse only the code you're interested in. For more information, see Outlining.

Screenshot of the outlining window shows the body of classes collapsed. Options for Collapse to Definitions, Toggle All Outlining, etc. are visible.

When you place your cursor in front of a curly brace, '{' or '}', the editor highlights its matching counterpart.

Other outlining options are located under Edit > Outlining in the main menu.

Line numbers

You can add line numbers to your project by going to Tools > Options > Text Editor > All Languages > General or by searching for "line num" with Quick Launch (Ctrl + Q). Line numbers can be set for all languages or for specific languages only, including C++.

Scroll and zoom

You can zoom in or out in the editor by pressing the Ctrl key and scrolling with your mouse wheel. You can also zoom by using the zoom setting in the bottom left corner.

Screenshot of the Zoom Control in the lower left of the screen. It's a dropdown with various zoom options like 133%.

Scrollbar Map Mode enables you to quickly scroll and browse through a code file without leaving your current location. You can click anywhere on the code map to go directly to that location.

Screenshot of the Code Map which shows an outline of the entire file on the right and a window displaying the code from the selected part of the map.

To turn on Map Mode, type "map" in the Quick Launch search box in the main toolbar and choose Use scroll map mode. For more information, see How to: Track your code by customizing the scrollbar.

When Map Mode is off, the scroll bar still highlights the changes you have made in the file. Green indicates saved changes and yellow indicates unsaved changes.

Quick Info and Parameter Info

Hover over any variable, function, or other symbol to get information about it, including the declaration, and any comments that are located just preceding it.

Screenshot of the Quick Info tooltip displaying the definition of a function that the user is hovering over in the code window.

The Quick Info tooltip has a Search Online link. Go to Tools > Options > Text Editor > C++ > View to specify the search provider.

If there's an error in your code, you can hover over it, and Quick Info will display the error message. You can also find the error message in the Error List window.

Screenshot of the Quick Info tooltip showing the error associated with a code squiggle.

Screenshot showing the Quick Info tooltip in Visual Studio 2017.

If there's an error in your code, you can hover over it, and Quick Info will display the error message. You can also find the error message in the Error List window.

Screenshot of the Quick Info tooltip showing the error associated with a code squiggle.

When you call a function, Parameter Info shows the types of parameters and the order in which they're expected.

Screenshot of parameter info showing the parameters for the function resize on vector v. The parameter info is: const size_t _Newsize, const int & _Val.

Peek Definition

Hover over a variable or function declaration, right-click, then choose Peek Definition to see an inline view of its definition without navigating away from your current location. For more information, see Peek Definition (Alt+F12).

Screenshot of the drop-down that appears when you right-click a function. Peek Definition appears in the menu along with the shortcut Alt + F 12.

F1 Help

Place the cursor on or just after any type, keyword or function and press F1 to go directly to the relevant reference topic on Microsoft Learn. F1 also works on items in the error list and in many dialog boxes.

Class View

Class View displays a searchable set of trees of all code symbols and their scope and parent/child hierarchies, organized on a per-project basis. You can configure what Class View displays from Class View Settings (click the gear box icon at the top of the window).

Screenshot of the Class View window displaying the classes in the project such as CipherFactory, FilterTester, and so on.

Generate graph of include files

Right click on a code file in your project and choose Generate graph of include files to see a graph of which files are included by other files.

Screenshot of a graph of include files. The graph shows that NAMSPACE DLL .CPP includes Namespace DLL .h, which includes V_10 .H, among other files.

View Call Hierarchy

Right click on any function call and view a recursive list of all the functions that it calls, and all the functions that call it. Each function in the list can be expanded in the same way. For more information, see Call Hierarchy.

Screenshot of the Call Hierarchy window which shows calls to and from Floating_to_wstring(). For example, to_wstring() calls Floating_to_wstring().

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