How to Debug C/C++ with VS Code
Summary
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
-Wand-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 -O0option
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