How to Debug C/C++ with VS Code

Summary

Basic
Spec
debugging Unit Test (cunit)
debugging executable file
debugging on Windows

Basic

GNU GCC
Extension: C/C++
Debugger: lldb(MacOS), gdb(Linux)
module code: bubble_sort.c

Spec

OS
- ✅ MacOS
- ✅ Windows * ✅ Linux
Break Point
- ✅ break point
- ✅ condition break point
- ✅ function breakpoint
Step Execution
- ✅ Step Over
- ✅ Step Into
- ✅ Step Out
- ✅ Continue
- ❌ Step Back
- ❌ Move To
- ❌ Pause
Variables
- ✅ variables views
- ✅ watch variables
Call Stack
- ✅ call stack
Evaluation
- ✅ eval expression to show variables
- ✅ eval expression to change variables
Type of Execution
- ✅ debug unit test
- ✅ debug executable package
- ✅ attach debug process (but cannot work on MacOS)
- ✅ remote debugging (but cannot start server on MacOS)

Instruction

MacOS

install XCode
install Extension C/C++

Windows

install Visual Studio 2017
install Extension C/C++

Linux

install gcc: sudo apt get -y gcc
install Extension C/C++

debugging unit test (cunit)

test code: bubble_sort_cunit.c

MacOS instruction

brew install cunit

Ubuntu instruction

sudo apt install libcunit1 libcunit1-dev

Windows instruction

HELP Wanted

launch.json

menu: C/C++: Launch

{
  "version": "0.2.0",
  "configurations": [
    {
      // for MacOS
      "name": "(lldb) Launch cunit",
      "type": "cppdbg",
      "request": "launch",
      "program": "${workspaceRoot}/bubble_sort_cunit",
      "args": [],
      "stopAtEntry": false,
      "cwd": "${workspaceRoot}",
      "environment": [],
      "externalConsole": true,
      "preLaunchTask": "build cunit",
      "MIMode": "lldb"
    },
    {
      // for Linux
      "name": "(gdb) Launch cunit",
      "type": "cppdbg",
      "request": "launch",
      "program": "${workspaceRoot}/a.out",
      "args": [],
      "stopAtEntry": false,
      "cwd": "${workspaceRoot}",
      "environment": [],
      "externalConsole": true,
      "MIMode": "gdb",
      "preLaunchTask": "build cunit",
      "setupCommands": [
        {
          "description": "Enable pretty-printing for gdb",
          "text": "-enable-pretty-printing",
          "ignoreFailures": true
        }
      ]
    }
  ]
}

how-to

build cunit

gcc bubble_sort.c bubble_sort_cunit.c -g -O0 -W -Wall -lcunit

Start "launch cunit"
new window is opened, and Run cunit

./a.out
***************** CUNIT CONSOLE - MAIN MENU ******************************
(R)un  (S)elect  (L)ist  (A)ctivate  (F)ailures  (O)ptions  (H)elp  (Q)uit
Enter command: R

gcc option for debugging

-W and -Wall : show warnings (not must)
-g : debug
-O0 : no optimisation
-lcunit : load cunit

debugging executable file (MacOS, Linux)

Program: main.c

launch.json

{
  "version": "0.2.0",
  "configurations": [
    {
      // MacOS
      "name": "Launch Program(lldb)",
      "type": "cppdbg",
      "request": "launch",
      "program": "${workspaceRoot}/a.out",
      "args": ["4", "3", "2", "1"],
      "stopAtEntry": false,
      "cwd": "${workspaceRoot}",
      "environment": [],
      "externalConsole": true,
      "MIMode": "lldb"
    },
    {
      // Linux
      "name": "(gdb) Launch",
      "type": "cppdbg",
      "request": "launch",
      "program": "${workspaceRoot}/a.out",
      "args": ["4", "3", "2", "1"],
      "stopAtEntry": false,
      "cwd": "${workspaceRoot}",
      "environment": [],
      "externalConsole": true,
      "MIMode": "gdb",
      "setupCommands": [
        {
          "description": "Enable pretty-printing for gdb",
          "text": "-enable-pretty-printing",
          "ignoreFailures": true
        }
      ]
    }
  ]
}

how-to

build with -g -O0 option

gcc bubble_sort.c main.c -g -O0 -W -Wall

Start "Launch Program"

debugging execute file (Windows)

launch.json

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "(Windows) Launch",
      "type": "cppvsdbg",
      "request": "launch",
      "program": "${workspaceRoot}/main.exe",
      "args": ["4", "3", "2", "1"],
      "stopAtEntry": false,
      "cwd": "${workspaceRoot}",
      "environment": [],
      "externalConsole": true
    }
  ]
}

how-to

Start Developer Command Prompt and build with /ZI option

cl main.c bubble_sort.c /ZI

Start debug.

attach to process

launch.json

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "(Linux gdb) Attach",
      "type": "cppdbg",
      "request": "attach",
      "program": "${workspaceFolder}/bubble_sort_cunit",
      "processId": "${command:pickProcess}",
      "MIMode": "gdb",
      "setupCommands": [
        {
          "description": "Enable pretty-printing for gdb",
          "text": "-enable-pretty-printing",
          "ignoreFailures": true
        }
      ]
    }
  ]
}

debug to remote machine (Mac/Linux to Linux)

With pipe transport, you'll debug remote linux from macos.

launch.json

set gdb path with sudo

{
  "version": "0.2.0",
  "configurations": [
		{
			"name": "(Mac to Linux)pipe transport",
			"type": "cppdbg",
			"request": "launch",
			"program": "/home/nnyn/Documents/vscode-debug-specs/cpp/main",
			"args": [
				"4",
				"3",
				"2",
				"1"
			],
			"stopAtEntry": false,
			"cwd": "/home/nnyn/Documents/vscode-debug-specs/cpp",
			"environment": [],
			"externalConsole": true,
			"pipeTransport": {
				"pipeCwd": "/usr/bin",
				"pipeProgram": "/usr/bin/ssh",
				"pipeArgs": [
					"nnyn@192.168.56.101"
				],
				"debuggerPath": "sudo /usr/bin/gdb"
			},
			"sourceFileMap": {
				// "remote": "local"
				"/home/nnyn/Documents/vscode-debug-specs/cpp": "${workspaceFolder}"
			},
			"MIMode": "gdb"
		},
	}
 ]

how to

build at remote machine

cd /home/nnyn/Documents/vscode-debug-specs/cpp
gcc -O0 -g -W -Wall -o main bubble_sort.c main.c

launch debug.

attach to remote process (Mac/Linux to Linux)

With pipe transport, you'll attach remote linux process from macos.

launch.json

{
  "version": "0.2.0",
  "configurations": [
		{
			"name": "(Mac to Linux)pipe transport attach",
			"type": "cppdbg",
			"request": "attach",
			"program": "/home/nnyn/Documents/vscode-debug-specs/cpp/bubble_sort_cunit",
			"processId": "21073",
			"pipeTransport": {
				"pipeCwd": "",
				"pipeProgram": "/usr/bin/ssh",
				"pipeArgs": [
					"nnyn@192.168.56.101"
				],
				"debuggerPath": "sudo /usr/bin/gdb"
			},
			"sourceFileMap": {
				// "remote": "local"
				"/home/nnyn/Documents/vscode-debug-specs/cpp": "${workspaceFolder}"
			},
			"MIMode": "gdb"
    }
	}
 ]

how to

build at remote machine
launch program at remote machine
check the process id of remote process
set the process id to launch.json
launch debug