Using C++ and WSL in VS Code

In this tutorial, you will configure Visual Studio Code to use the GCC C++ compiler (g++) and GDB debugger on Ubuntu in theWindows Subsystem for Linux (WSL). GCC stands for GNU Compiler Collection; GDB is the GNU debugger. WSL is a Linux environment within Windows that runs directly on the machine hardware, not in a virtual machine.

Note: Much of this tutorial is applicable to working with C++ and VS Code directly on a Linux machine.

Visual Studio Code has support for working directly in WSL with theWSL extension. We recommend this mode ofWSL development, where all your source code files, in addition to the compiler, are hosted on the Linux distro. For more background, seeVS Code Remote Development.

After completing this tutorial, you will be ready to create and configure your own C++ project, and to explore the VS Code documentation for further information about its many features. This tutorial does not teach you about GCC or Linux or the C++ language. For those subjects, there are many good resources available on the Web.

If you have any problems, feel free to file an issue for this tutorial in theVS Code documentation repository.

Prerequisites

To successfully complete this tutorial, you must do the following steps:

1. InstallVisual Studio Code.

2. Install theWSL extension.

3. InstallWindows Subsystem for Linux and then use the links on that same page to install your Linux distribution of choice. This tutorial uses Ubuntu. During installation, remember your Linux user password because you'll need it to install additional software.

Set up your Linux environment

1. Open the Bash shell for WSL. If you installed an Ubuntu distro, type "Ubuntu" in the Windows search box and then click on it in the result list. For Debian, type "Debian", and so on.

   

   The shell appears with a command prompt that by default consists of your user name and computer name, and puts you in your home directory. For Ubuntu it looks like this:

   

2. Make a directory calledprojects and then subdirectory under that calledhelloworld:

   mkdir projectscd projectsmkdir helloworld

3. Although you will be using VS Code to edit your source code, you'll be compiling the source code on Linux using the g++ compiler. You'll also debug on Linux using GDB. These tools are not installed by default on Ubuntu, so you have to install them. Fortunately, that task is quite easy!

4. From the WSL command prompt, first runapt-get update to update the Ubuntu package lists. An out-of-date distro can sometimes interfere with attempts to install new packages.

   sudo apt-get update

   If you like, you can runsudo apt-get update && sudo apt-get dist-upgrade to also download the latest versions of the system packages, but this can take significantly longer depending on your connection speed.

5. From the command prompt, install the GNU compiler tools and the GDB debugger by typing:

   sudo apt-get install build-essential gdb

6. Verify that the install succeeded by locating g++ and gdb. If the filenames are not returned from thewhereis command, try running the update command again.

   whereis g++whereis gdb

Note: The setup steps for installing the g++ compiler and GDB debugger apply if you are working directly on a Linux machine rather than in WSL. Running VS Code in your helloworld project, as well as the editing, building, and debugging steps are the same.

Run VS Code in WSL

Navigate to your helloworld project folder and launch VS Code from the WSL terminal withcode .:

cd $HOME/projects/helloworldcode .

You'll see a message about "Installing VS Code Server". VS Code is downloading and installing a small server on the Linux side that the desktop VS Code will then talk to. VS Code will then start and open thehelloWorld folder. The File Explorer shows that VS Code is now running in the context of WSL with the title barWSL: Ubuntu.

You can also tell the remote context from the Status bar.

If you click on the Remote Status bar item, you will see a dropdown of Remote commands appropriate for the session. For example, if you want to end your session running in WSL, you can select theClose Remote Connection command from the dropdown. Runningcode . from your WSL command prompt will restart VS Code running in WSL.

Thecode . command opened VS Code in the current working folder, which becomes your "workspace". As you go through the tutorial, you will see three files created in a.vscode folder in the workspace:

• c_cpp_properties.json (compiler path and IntelliSense settings)
• tasks.json (build instructions)
• launch.json (debugger settings)

Add a source code file

In the File Explorer title bar, select theNew File button and name the filehelloworld.cpp.

Install the C/C++ extension

Once you create the file and VS Code detects it is a C++ language file, you may be prompted to install theMicrosoft C/C++ extension if you don't already have it installed.

ChooseInstall and thenReload Required when the button is displayed in the Extensions view to complete installing the C/C++ extension.

If you already have C/C++ language extensions installed locally in VS Code, you'll need to go to the Extensions view (⇧⌘X (Windows, LinuxCtrl+Shift+X)) and install those extensions into WSL. Locally installed extensions can be installed into WSL by selecting theInstall in WSL button and thenReload Required.

Add hello world source code

Now paste in this source code:

#include <iostream>#include <vector>#include <string>using namespace std;int main(){   vector<string> msg {"Hello","C++","World","from","VS Code","and the C++ extension!"};   for (const string& word : msg)   {      cout << word <<" ";   }   cout << endl;}

Now press⌘S (Windows, LinuxCtrl+S) to save the file. Notice how the file you just added appears in theFile Explorer view (⇧⌘E (Windows, LinuxCtrl+Shift+E)) in the side bar of VS Code:

You can also enableAuto Save to automatically save your file changes, by checkingAuto Save in the mainFile menu.

The Activity Bar on the far left lets you open different views such asSearch,Source Control, andRun. You'll look at theRun view later in this tutorial. You can find out more about the other views in the VS CodeUser Interface documentation.

Explore IntelliSense

In your newhelloworld.cpp file, hover overvector orstring to see type information. After the declaration of themsg variable, start typingmsg. as you would when calling a member function. You should immediately see a completion list that shows all the member functions, and a window that shows the type information for themsg object:

You can press theTab key to insert the selected member; then, when you add the opening parenthesis, you will see information about any arguments that the function requires.

Run helloworld.cpp

Remember, the C++ extension uses the C++ compiler you have installed on your machine to build your program. Make sure you have a C++ compiler installed before attempting to run and debughelloworld.cpp in VS Code.

1. Openhelloworld.cpp so that it is the active file.

2. Press the play button in the top right corner of the editor.

   

3. Chooseg++ build and debug active file from the list of detected compilers on your system.

   

You'll only be asked to choose a compiler the first time you runhelloworld.cpp. This compiler will be set as the "default" compiler intasks.json file.

4. After the build succeeds, your program's output will appear in the integratedTerminal.

   

The first time you run your program, the C++ extension createstasks.json, which you'll find in your project's.vscode folder.tasks.json stores build configurations.

Your newtasks.json file should look similar to the JSON below:

{  "version":"2.0.0",  "tasks": [    {      "type":"shell",      "label":"C/C++: g++ build active file",      "command":"/usr/bin/g++",      "args": ["-g","${file}","-o","${fileDirname}/${fileBasenameNoExtension}"],      "options": {        "cwd":"/usr/bin"      },      "problemMatcher": ["$gcc"],      "group": {        "kind":"build",        "isDefault":true      },      "detail":"Task generated by Debugger."    }  ]}

Note: You can learn more abouttasks.json variables in thevariables reference.

Thecommand setting specifies the program to run; in this case that is g++.Theargs array specifies the command-line arguments that will be passed to g++. These arguments must be specified in the order expected by the compiler.

This task tells g++ to take the active file (${file}), compile it, and create an executable file in the current directory (${fileDirname}) with the same name as the active file but without an extension (${fileBasenameNoExtension}), resulting inhelloworld for our example.

Thelabel value is what you will see in the tasks list; you can name this whatever you like.

Thedetail value is what you will as the description of the task in the tasks list. It's highly recommended to rename this value to differentiate it from similar tasks.

From now on, the play button will read fromtasks.json to figure out how to build and run your program. You can define multiple build tasks intasks.json, and whichever task is marked as the default will be used by the play button. In case you need to change the default compiler, you can runTasks: Configure default build task. Alternatively you can modify thetasks.json file and remove the default by replacing this segment:

    "group": {        "kind":"build",        "isDefault":true    },

with this:

    "group":"build",

Modifying tasks.json

You can modify yourtasks.json to build multiple C++ files by using an argument like"${workspaceFolder}/*.cpp" instead of"${file}".This will build all.cpp files in your current folder. You can also modify the output filename by replacing"${fileDirname}/${fileBasenameNoExtension}" with a hard-coded filename (for example 'helloworld.out').

Debug helloworld.cpp

To debug your code,

1. Go back tohelloworld.cpp so that it is the active file.
2. Set a breakpoint by clicking on the editor margin or using F9 on the current line.
3. From the drop-down next to the play button, selectDebug C/C++ File.
4. ChooseC/C++: g++ build and debug active file from the list of detected compilers on your system (you'll only be asked to choose a compiler the first time you run ordebughelloworld.cpp).

The play button has two modes:Run C/C++ File andDebug C/C++ File. It will default to the last-used mode. If you see the debug icon in the play button, you can select the play button to debug, instead of selecting the drop-down menu item.

Explore the debugger

Before you start stepping through the code, let's take a moment to notice several changes in the user interface:

• The Integrated Terminal appears at the bottom of the source code editor. In theDebug Output tab, you see output that indicates the debugger is up and running.

• The editor highlights line 12, which is a breakpoint that you set before starting the debugger:

  

• TheRun and Debug view on the left shows debugging information. You'll see an example later in the tutorial.

• At the top of the code editor, a debugging control panel appears. You can move this around the screen by grabbing the dots on the left side.

  

If you already have a launch.json file in your workspace, the play button will read from it when figuring out how run and debug your C++ file. If you don’t have launch.json, the play button will create a temporary “quick debug” configuration on the fly, eliminating the need for launch.json altogether!

Step through the code

Now you're ready to start stepping through the code.

1. Click or press theStep over icon in the debugging control panel.

   

   This will advance program execution to the first line of the for loop, and skip over all the internal function calls within thevector andstring classes that are invoked when themsg variable is created and initialized. Notice the change in theVariables window on the side.

   

2. PressStep over again to advance to the next statement in this program (skipping over all the internal code that is executed to initialize the loop). Now, theVariables window shows information about the loop variables.

3. PressStep over again to execute thecout statement. (Note that the C++ extension does not print any output to theDebug Console until the last cout executes.)

4. If you like, you can keep pressingStep over until all the words in the vector have been printed to the console. But if you are curious, try pressing theStep Into button to step through source code in the C++ standard library!

   

   To return to your own code, one way is to keep pressingStep over. Another way is to set a breakpoint in your code by switching to thehelloworld.cpp tab in the code editor, putting the insertion point somewhere on thecout statement inside the loop, and pressingF9. A red dot appears in the gutter on the left to indicate that a breakpoint has been set on this line.

   

   Then pressF5 to start execution from the current line in the standard library header. Execution will break oncout. If you like, you can pressF9 again to toggle off the breakpoint.

   When the loop has completed, you can see the output in theDebug Console tab of the integrated terminal, along with some other diagnostic information that is output by GDB.

   

Set a watch

To keep track of the value of a variable as your program executes, set awatch on the variable.

1. Place the insertion point inside the loop. In theWatch window, click the plus sign and in the text box, typeword, which is the name of the loop variable. Now view the Watch window as you step through the loop.

   

2. To quickly view the value of any variable while execution is paused on a breakpoint, you can hover over it with the mouse pointer.

   

Next, you'll create atasks.json file to tell VS Code how to build (compile) the program. This task will invoke the g++ compiler to create an executable file from the source code.

It's important to havehelloworld.cpp open in the editor because the next step uses the active file in the editor for context to create the build task in the next step.

Customize debugging with launch.json

When you debug with the play button orF5, the C++ extension creates a dynamic debug configuration on the fly.

There are cases where you'd want to customize your debug configuration, such as specifying arguments to pass to the program at runtime. You can define custom debug configurations in alaunch.json file.

To createlaunch.json, chooseAdd Debug Configuration from the play button drop-down menu.

You'll then see a dropdown for various predefined debugging configurations. Chooseg++ build and debug active file.

VS Code creates alaunch.json file, which looks something like this:

{  "version":"0.2.0",  "configurations": [    {      "name":"C/C++: g++ build and debug active file",      "type":"cppdbg",      "request":"launch",      "program":"${fileDirname}/${fileBasenameNoExtension}",      "args": [],      "stopAtEntry":false,      "cwd":"${workspaceFolder}",      "environment": [],      "externalConsole":false,      "MIMode":"gdb",      "miDebuggerPath":"/usr/bin/gdb",      "setupCommands": [        {          "description":"Enable pretty-printing for gdb",          "text":"-enable-pretty-printing",          "ignoreFailures":true        }      ],      "preLaunchTask":"C/C++: g++ build active file"    }  ]}

In the JSON above,program specifies the program you want to debug. Here it is set to the active file folder${fileDirname} and active filename without an extension${fileBasenameNoExtension}, which ifhelloworld.cpp is the active file will behelloworld. Theargs property is an array of arguments to pass to the program at runtime.

By default, the C++ extension won't add any breakpoints to your source code and thestopAtEntry value is set tofalse.

Change thestopAtEntry value totrue to cause the debugger to stop on themain method when you start debugging.

From now on, the play button andF5 will read from yourlaunch.json file when launching your program for debugging.

C/C++ configurations

If you want more control over the C/C++ extension, you can create ac_cpp_properties.json file, which will allow you to change settings such as the path to the compiler, include paths, C++ standard (default is C++17), and more.

You can view the C/C++ configuration UI by running the commandC/C++: Edit Configurations (UI) from the Command Palette (⇧⌘P (Windows, LinuxCtrl+Shift+P)).

This opens theC/C++ Configurations page. When you make changes here, VS Code writes them to a file calledc_cpp_properties.json in the.vscode folder.

You only need to modify theInclude path setting if your program includes header files that are not in your workspace or in the standard library path.

Visual Studio Code places these settings in.vscode/c_cpp_properties.json. If you open that file directly, it should look something like this:

{  "configurations": [    {      "name":"Linux",      "includePath": ["${workspaceFolder}/**"],      "defines": [],      "compilerPath":"/usr/bin/gcc",      "cStandard":"c11",      "cppStandard":"c++17",      "intelliSenseMode":"clang-x64"    }  ],  "version":4}

Closing the WSL session

When you are done working in WSL, you can close your remote session with theClose Remote Connection command available in the mainFile menu and the Command Palette (⇧⌘P (Windows, LinuxCtrl+Shift+P)). This will restart VS Code running locally. You can easily reopen your WSL session from theFile >Open Recent list by selecting folders with the[WSL] suffix.

Next steps

• Explore theVS Code User Guide.
• Review theOverview of the C++ extension.
• Create a new workspace, copy your .json files to it, adjust the necessary settings for the new workspace path, program name, and so on, and start coding!