VS Code Debugger

Debugger configurations for Visual Studio Code

The launch.json file defines debug configurations for Visual Studio Code. This page includes examples demonstrating common launch.json setups.

Visual Studio Code Documentation

Debug Configuration

Procedure

1. Open the workspace directory in VS Code.
2. In the workspace root, create a .vscode directory if it does not already exist.
3. Inside .vscode, create a file named launch.json.

Python Example

Example Python Program

#_______________________________________________________________
# This file is named arg_test.py
#_______________________________________________________________
import argparse

if __name__ == '__main__':
  parser: argparse.ArgumentParser = argparse.ArgumentParser()
  parser.add_argument('--in0', '-i0', help='Input 0', action='store')
  parser.add_argument('--in1', '-i1', help='Input 1', action='store')
  args: argparse.Namespace = parser.parse_args()

  print(str(
    f'\nInput argument 0: {args.in0}'
    f'\nInput argument 1: {args.in1}'
    )
  )

Sample launch.json

This launch.json file contains two Python debug configurations with alternative inputs.

{ "version":        "0.2.0"

, "configurations":
  [ { "name"    : "sample py debug"
    , "type"    : "debugpy"
    , "request" : "launch"
    , "program" : "${workspaceFolder}/arg_test.py"
    , "console" : "integratedTerminal"
    , "args"    :
      [ "--in0", "42"
      , "-i1"  , "3.14"
      ]
    }

  , { "name"    : "alternate input sample py"
    , "type"    : "debugpy"
    , "request" : "launch"
    , "program" : "${workspaceFolder}/arg_test.py"
    , "console" : "integratedTerminal"
    , "args"    :
      [ "--in0", "64"
      , "--in1", "4096"
      ]
    }
  ]
}

Key Descriptions

Key	Description
name	Name of configuration.
type	Type of debugger. Common values are debugpy for python, gdb for cpp.
request	Specifies what kind of debugging action VS Code should perform. launch = Start a new program attach = Attach debugger to a program that is already running.
program	Path to program to execute.
console	Use integratedTerminal to use the VS Code terminal for program execution.
args	Arguments passed to the program.

Run Debug Configuration

1. Select the icon for Run and Debug from the activity bar. Click the drop down menu and select a configuration in launch.json.

   

2. Click the triangle (▷) play symbol to run the debug configuration.

C++ Example

Notes

1. Debugging a C++ program requires debug symbols. When using g++, enable them with the -g command-line option.
2. You can create a VS Code task to build the C++ program using debug symbols.

Example C++ Program

#include <cstdio>
#include <cstdlib>

int main(int argc, char* argv[])
{
  int i = -1;

  // Convert command line input C-style string (e.g. char*) to integer
  if (argc > 1)
  {
    i = std::atoi(argv[1]);
  }

  printf(
    "\n\nHello there :)"
    "\n\nInput argument: %d"
    "\n\n"
    , i
  );

  return 0;
}

Sample launch.json C++ Configuration

{ "version": "0.2.0"
, "configurations":
  [ { "name"            : "hello-cpp-debug"
    , "type"            : "cppdbg"
    , "request"         : "launch"
    , "cwd"             : "${workspaceFolder}"
    , "program"         : "${workspaceFolder}/hello/hello.out"
    , "args"            : ["42"]
    , "stopAtEntry"     : true
    , "externalConsole" : false
    }
  ]
}

Key Descriptions

Key	Description
name	Name of configuration.
type	Type of debugger. Common value for C++ is “cppdbg”
request	Specifies what kind of debugging action VS Code should perform. launch = Start a new program attach = Attach debugger to a program that is already running.
cwd	Defines the working directory used when running the command.
program	Path to program to execute.
args	Arguments passed to the program.
stopAtEntry	Sets a breakpoint at program entry.
externalConsole	Use integratedTerminal to use the VS Code terminal for program execution.

Sample tasks.json C++ Debug Build

The following tasks.json example defines a VS Code task that builds a C++ program with debug symbols using the -g option of g++.

{ "version": "2.0.0"
, "tasks":
  [
    { "label"   : "compile-hello-debug"
    , "type"    : "shell"
    , "command" : "g++"
    , "args"    :
      [ "${workspaceFolder}/hello/hello.cpp"
      , "-g"
      , "-o"
      , "${workspaceFolder}/hello/hello.out"
      ]

      // Close task terminal after execution
    , "presentation"  :
      { "close": true
      }

      // Disable error detection for task
    , "problemMatcher": []
    }
  ]
}