Setting Up VS Code to Compile and Run C++ (Mac)

What You’ll Need

  • Visual Studio Code
  • C++ compiler (clang for Mac)
  • VS Code C++ extensions

Step 1 — Install Xcode Command Line Tools

Open Terminal and run:

xcode-select --install

Follow the prompt. When done, verify it worked:

clang++ --version

You should see something like Apple clang version 15.x.x.

Step 2 — Install Visual Studio Code

Download and install from: https://code.visualstudio.com

Step 3 — Install C++ Extensions in VS Code

  1. Open VS Code
  2. Go to the Extensions tab (left sidebar or Cmd+Shift+X)
  3. Search for and install:
    • C/C++ by Microsoft
    • C/C++ Extension Pack by Microsoft (includes the debugger and IntelliSense)

Step 4 — Create and Run a Simple C++ Program

  1. Create a new folder for your project (e.g., cpp-labs)
  2. Open the folder in VS Code: File → Open Folder
  3. Create a new file: hello.cpp

Paste the following:

#include <iostream>

int main() {
    std::cout << "Hello, world!" << std::endl;
    return 0;
}
  1. Open the Terminal in VS Code: Terminal → New Terminal
  2. Compile the code:
clang++ hello.cpp -o hello
  1. Run the program:
./hello

You should see: Hello, world!

Step 5 — Configure VS Code to Build with One Keystroke

Instead of typing compile commands every time, set up a VS Code build task.

Create the tasks file

  1. In VS Code, go to Terminal → Configure Default Build Task
  2. Select C/C++: clang++ build active file

VS Code will create a .vscode/tasks.json file. Replace its contents with this:

{
  "version": "2.0.0",
  "tasks": [
    {
      "label": "Build C++",
      "type": "shell",
      "command": "clang++",
      "args": [
        "-g",
        "-std=c++17",
        "${file}",
        "-o",
        "${fileDirname}/${fileBasenameNoExtension}"
      ],
      "group": {
        "kind": "build",
        "isDefault": true
      },
      "problemMatcher": ["$gcc"]
    }
  ]
}

Note: The -g flag includes debug information — required for the debugger to work. The -std=c++17 flag enables modern C++ features.

Now build any open .cpp file by pressing Cmd+Shift+B.

Step 6 — Set Up the Debugger

The debugger lets you pause your program mid-execution, inspect variables, and step through code line by line.

Create the launch configuration

  1. Click the Run and Debug icon in the left sidebar (or press Cmd+Shift+D)
  2. Click create a launch.json file
  3. Select C++ (GDB/LLDB), then clang++ — Build and debug active file

VS Code will create .vscode/launch.json. Replace its contents with:

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Build and Debug",
      "type": "lldb",
      "request": "launch",
      "program": "${fileDirname}/${fileBasenameNoExtension}",
      "args": [],
      "cwd": "${fileDirname}",
      "preLaunchTask": "Build C++"
    }
  ]
}

Note: This uses lldb, the debugger that ships with Xcode on Mac. If you see an error about lldb, install the CodeLLDB extension from the VS Code marketplace.

Debugger Controls

Action How
Set a breakpoint Click in the gutter (left of the line number) — a red dot appears
Start debugging F5 or click the green play button
Step over a line F10 — runs the line, stays at the same level
Step into a function F11 — follows the call inside the function
Step out Shift+F11 — finishes the function and returns
Continue to next breakpoint F5
Stop debugging Shift+F5
Inspect a variable Hover over it while paused, or check the Variables panel

Step 7 — Try It with a Larger Program

Here’s a student grade tracker with enough complexity to make debugging practice worthwhile. It uses functions, loops, vectors, and structs.

Create a new file called grades.cpp and paste this in:

#include <iostream>
#include <vector>
#include <string>
#include <numeric>
#include <algorithm>
#include <iomanip>

struct Student {
    std::string name;
    std::vector<double> scores;
};

double average(const std::vector<double>& scores) {
    if (scores.empty()) return 0.0;
    double total = std::accumulate(scores.begin(), scores.end(), 0.0);
    return total / scores.size();
}

char letterGrade(double avg) {
    if (avg >= 90) return 'A';
    if (avg >= 80) return 'B';
    if (avg >= 70) return 'C';
    if (avg >= 60) return 'D';
    return 'F';
}

double highest(const std::vector<double>& scores) {
    return *std::max_element(scores.begin(), scores.end());
}

double lowest(const std::vector<double>& scores) {
    return *std::min_element(scores.begin(), scores.end());
}

void printStudentReport(const Student& s) {
    double avg = average(s.scores);
    std::cout << "\nStudent: " << s.name << "\n";
    std::cout << "  Scores:  ";
    for (double score : s.scores) {
        std::cout << std::setw(6) << score;
    }
    std::cout << "\n";
    std::cout << std::fixed << std::setprecision(1);
    std::cout << "  Average: " << avg << "\n";
    std::cout << "  Highest: " << highest(s.scores) << "\n";
    std::cout << "  Lowest:  " << lowest(s.scores) << "\n";
    std::cout << "  Grade:   " << letterGrade(avg) << "\n";
}

void printClassSummary(const std::vector<Student>& students) {
    std::cout << "\n========== Class Summary ==========\n";
    double classTotal = 0.0;
    std::string topStudent;
    double topAvg = -1.0;

    for (const Student& s : students) {
        double avg = average(s.scores);
        classTotal += avg;
        if (avg > topAvg) {
            topAvg = avg;
            topStudent = s.name;
        }
    }

    double classAvg = classTotal / students.size();
    std::cout << std::fixed << std::setprecision(1);
    std::cout << "Number of students: " << students.size() << "\n";
    std::cout << "Class average:      " << classAvg << " (" << letterGrade(classAvg) << ")\n";
    std::cout << "Top student:        " << topStudent << " (" << topAvg << ")\n";

    int countA = 0, countB = 0, countC = 0, countD = 0, countF = 0;
    for (const Student& s : students) {
        char g = letterGrade(average(s.scores));
        if (g == 'A') countA++;
        else if (g == 'B') countB++;
        else if (g == 'C') countC++;
        else if (g == 'D') countD++;
        else countF++;
    }

    std::cout << "\nGrade distribution:\n";
    std::cout << "  A: " << countA << "\n";
    std::cout << "  B: " << countB << "\n";
    std::cout << "  C: " << countC << "\n";
    std::cout << "  D: " << countD << "\n";
    std::cout << "  F: " << countF << "\n";
}

int main() {
    std::vector<Student> roster = {
        {"Alice",   {92, 88, 95, 91, 84}},
        {"Bob",     {73, 65, 70, 68, 72}},
        {"Carol",   {85, 90, 88, 93, 96}},
        {"David",   {55, 60, 58, 62, 50}},
        {"Eva",     {78, 82, 79, 81, 76}},
        {"Frank",   {100, 98, 95, 99, 97}},
        {"Grace",   {40, 45, 38, 50, 42}},
    };

    std::cout << "========== Individual Reports ==========";
    for (const Student& s : roster) {
        printStudentReport(s);
    }

    printClassSummary(roster);
    return 0;
}

Compile and run it

clang++ -g -std=c++17 grades.cpp -o grades
./grades

Things to try with the debugger

  1. Set a breakpoint on the printStudentReport call inside the for loop in main. Press F5. The program pauses for each student — expand the s variable in the Variables panel to see their name and scores.
  2. Step into average() from inside printStudentReport using F11. Watch total grow as accumulate runs.
  3. Step over lines in printClassSummary and watch topStudent and topAvg update as each student is evaluated.
  4. Hover over variables while paused — VS Code shows their current value inline.

Quick Reference

Task Shortcut
Build Cmd+Shift+B
Start / continue debugging F5
Step over F10
Step into F11
Step out Shift+F11
Stop debugging Shift+F5
Toggle breakpoint Click gutter or F9
Open terminal Ctrl+`

Troubleshooting

“lldb not found” or debugger won’t start
Install the CodeLLDB extension in VS Code, then make sure launch.json has "type": "lldb".

“command not found: clang++”
Re-run xcode-select --install in Terminal and make sure the installation completed.

Breakpoints are grey (unverified)
Make sure you compiled with the -g flag. Without it, the debugger has no line information.

Changes to code don’t show up when debugging
Always rebuild (Cmd+Shift+B) before starting a new debug session, or use the Build and Debug launch config which rebuilds automatically.

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