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.NET Thailand

Debugging in VS Code

Debug C# Code

  • Create .vscode/launch.json file.

  • Add the following content and change program value to your output file.

    {
      "version": "0.2.0",
      "configurations": [
        {
          "name": ".NET Core Launch (console)",
          "type": "coreclr",
          "request": "launch",
          "preLaunchTask": "build",
          // TODO Change program value to your output file.
          // If you have changed target frameworks, make sure to update the program path.",
          "program": "${workspaceFolder}/bin/Debug/net5.0/MyProgram.dll",
          "args": [],
          "cwd": "${workspaceFolder}",
          "console": "internalConsole",
          "stopAtEntry": false
        }
      ]
    }

  • Create .vscode/tasks.json file.

  • Add the following content and use your project file.

    {
      "version": "2.0.0",
      "tasks": [
        {
          "label": "build",
          "command": "dotnet",
          "type": "process",
          "args": [
            "build",
            // TODO Change a value to your project file.
            "${workspaceFolder}/MyProgram.csproj",
            "/property:GenerateFullPaths=true",
            "/consoleloggerparameters:NoSummary"
          ],
          "problemMatcher": "$msCompile"
        }
      ]
    }

  • Alternatively you can use VS Code to generate launch.json and tasks.json.

    1. Click Debug icon.
    2. Click create a launch.json file.
    3. Click .NET Core.

    Create launch.json by VS Code

  • Open a project with VS Code.

  • Put a breakpoint (F9) on a line that you want to pause a program and inspect value of a variable.

  • Start a program by pressing F5 or go to Run > Start Debugging.

    • If you want to debug LINQ, put a cursor on Lambda expression and go to Run > New Breakpoint > Inline Breakpoint.
    • You can also put a cursor on a lambda expression and press F9.

  • A program will be launched and pause on a line that you put a breakpoint.

  • You can inspect current values of variables in variable window, add variable to watch and see call stack.

    debug LINQ in VS Code

Debug with an external terminal WSL2

  • If we set "console": "externalTerminal" option in launch.json, we will get Unable to launch debugger worker process (vsdbg) through the terminal. spawn xterm ENOENT error message.

  • We can use dotnet run in an external terminal to run our .NET project and then attach a debugger.

  • For a console app, we may need to add checking Debugger.IsAttached at the beginning of the main method as the following code:

        public static void Main(string[] args)
        {
            while (!Debugger.IsAttached)
            {
                Thread.Sleep(100);
            }
        }

  • Add .NET Core Attach configuration to launch.json file.

    {
      "version": "0.2.0",
      "configurations": [
        {
          "name": ".NET Core Attach",
          "type": "coreclr",
          "request": "attach"
        }
      ]
    }

  • In an external terminal, CD to the root of our project and execute dotnet run.

    Terminal window
    $ dotnet run

  • Go back to VS Code. Put a breakpoint to a line that you want a pause a program.

  • Click Debug icon.

  • Change to .NET Core Attach configuration.

  • Click Start Debugging button or press F5.

  • Select a process that has a name matches to our project name.

  • A program has been paused at a breakpoint and we can now start debugging, inspecting a value.

Credit & useful resources