Choose C/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 or debug helloworld.cpp).
The play button has two modes: Run C/C++ File and Debug C/C++ File. It will default to the last-used mode. If you see the debug icon in the play button, you can just 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 the Debug 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:
The Run 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.
Click or press the Step 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 the vector and string classes that are invoked when the msg variable is created and initialized. Notice the change in the Variables window on the side.
Press Step 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, the Variables window shows information about the loop variables.
Press Step over again to execute the cout statement. (Note that the C++ extension does not print any output to the Debug Console until the last cout executes.)
If you like, you can keep pressing Step over until all the words in the vector have been printed to the console. But if you are curious, try pressing the Step Into button to step through source code in the C++ standard library!
To return to your own code, one way is to keep pressing Step over. Another way is to set a breakpoint in your code by switching to the helloworld.cpp tab in the code editor, putting the insertion point somewhere on the cout statement inside the loop, and pressing F9. A red dot appears in the gutter on the left to indicate that a breakpoint has been set on this line.
Then press F5 to start execution from the current line in the standard library header. Execution will break on cout. If you like, you can press F9 again to toggle off the breakpoint.
When the loop has completed, you can see the output in the Debug 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 a watch on the variable.
Place the insertion point inside the loop. In the Watch window, click the plus sign and in the text box, type word, which is the name of the loop variable. Now view the Watch window as you step through the loop.
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 a tasks.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 have helloworld.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 or F5, 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 a launch.json file.
To create launch.json, choose Add Debug Configuration from the play button drop-down menu.
You'll then see a dropdown for various predefined debugging configurations. Choose g++ build and debug active file.
VS Code creates a launch.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 ${fileBasenameNoExtension}, which if helloworld.cpp is the active file will be helloworld. The args property is an array of arguments to pass to the program at runtime.
By default, the C++ extension won't add any breakpoints to your source code and the stopAtEntry value is set to false.
Change the stopAtEntry value to true to cause the debugger to stop on the main method when you start debugging.
From now on, the play button and F5 will read from your launch.json file when launching your program for debugging.
C/C++ configurations
If you want more control over the C/C++ extension, you can create a c_cpp_properties.json file, which will allow you to change settings such as the path to the compiler, include paths, C++ standard (default is C++17), and more.
You can view the C/C++ configuration UI by running the command C/C++: Edit Configurations (UI) from the Command Palette (⇧⌘P (Windows, Linux Ctrl+Shift+P)).
This opens the C/C++ Configurations page. When you make changes here, VS Code writes them to a file called c_cpp_properties.json in the .vscode folder.
You only need to modify the Include path setting if your program includes header files that are not in your workspace or in the standard library path.
Visual Studio Code places these settings in .vscode/c_cpp_properties.json. If you open that file directly, it should look something like this:
"configurations": [
"name": "Linux",
"includePath": ["${workspaceFolder}/**"],
"defines": [],
"compilerPath": "/usr/bin/gcc",
"cStandard": "c11",
"cppStandard": "c++17",
"intelliSenseMode": "clang-x64"
"version": 4
Reusing your C++ configuration
VS Code is now configured to use gcc on Linux. The configuration applies to the current workspace. To reuse the configuration, just copy the JSON files to a .vscode folder in a new project folder (workspace) and change the names of the source file(s) and executable as needed.
Troubleshooting
Compiler and linking errors
The most common cause of errors (such as undefined _main, or attempting to link with file built for unknown-unsupported file format, and so on) occurs when helloworld.cpp is not the active file when you start a build or start debugging. This is because the compiler is trying to compile something that isn't source code, like your launch.json, tasks.json, or c_cpp_properties.json file.
Next steps
