Run C++ Code from Python – Step-by-Step Guide | PyShine

Run C++ Code from Python – Step-by-Step Guide

Beginner-Friendly Tutorial – Learn How Python Can Compile and Execute C++ Code

Python is an incredibly versatile language, but sometimes you might need the speed and performance of C++. This tutorial explains how to run C++ code directly from Python, making it easy to integrate both languages. You’ll learn how to write, compile, and execute a temporary C++ program from a Python script using the subprocess and tempfile modules. This is a great way to understand cross-language execution and automation using Python!

Table of Contents

Overview

This project shows how Python can act as a controller for compiling and executing C++ code. The program:

  1. Writes a simple C++ Hello World program to a temporary file.
  2. Uses subprocess.run() to compile it using the g++ compiler.
  3. Executes the compiled program and displays the C++ output inside Python.
  4. Cleans up all temporary files automatically.

Why Run C++ from Python?

  • Combine Python’s flexibility with C++’s performance.
  • Automate testing of C++ code or generate code dynamically.
  • Build hybrid systems where Python handles logic and C++ handles computation-heavy tasks.

Step 1: Writing C++ Code in Python

The script starts with a simple Python print, followed by defining C++ code as a multi-line string.

import subprocess  # To run external programs
import tempfile    # To create temporary files for C++ code
import os          # To handle file operations

print("Hello World from Python!")  # Simple Python print

cpp_code = """
#include <iostream>
using namespace std;

int main() {
    cout << "Hello World from C++!" << endl;
    return 0;
}
"""

Here, the C++ code is stored as a string that will later be written to a temporary file.

Setting Up g++ on Your System

You need a working C++ compiler (g++) to run this tutorial. Follow the steps below depending on your OS.

Windows

  1. Install MinGW-w64 (Minimalist GNU for Windows):
  2. Add the bin directory (e.g., C:\mingw64\bin) to your PATH environment variable.
  3. Open Command Prompt and type:
    g++ --version

    If it prints version info, you’re ready to go!

macOS

  1. Install Xcode Command Line Tools by running:
    xcode-select --install
  2. Verify installation with:
    g++ --version

    You should see Apple’s clang compiler, which works for this tutorial.

Linux (Ubuntu/Debian)

  1. Open Terminal and install g++:
    sudo apt update
sudo apt install g++
  2. Verify installation:
    g++ --version

Step 2: Compiling C++ Code

We create a temporary .cpp file and compile it using the g++ compiler.

with tempfile.NamedTemporaryFile(delete=False, suffix=".cpp") as f:
    cpp_file = f.name
    f.write(cpp_code.encode())

exe_file = cpp_file.replace(".cpp", "")

compile_proc = subprocess.run(
    ["g++", cpp_file, "-o", exe_file],
    capture_output=True,
    text=True
)
  • tempfile.NamedTemporaryFile() creates a unique .cpp file in the system’s temporary directory.
  • subprocess.run() executes the g++ compiler to compile the file into an executable.
  • capture_output=True captures any compilation messages.

Step 3: Executing the Compiled Program

After successful compilation, Python runs the compiled C++ binary.

if compile_proc.returncode != 0:
    print("C++ compilation failed!")
    print(compile_proc.stderr)
else:
    result = subprocess.run([exe_file], capture_output=True, text=True)
    print("Output from C++:")
    print(result.stdout.strip())

If compilation fails, Python displays the compiler error messages. If it succeeds, it prints the C++ program output.

Example Output:

Hello World from Python!
Output from C++:
Hello World from C++!

Step 4: Cleaning Up Temporary Files

Finally, we remove temporary files created during compilation.

os.remove(cpp_file)
if os.path.exists(exe_file):
    os.remove(exe_file)

This ensures no leftover files clutter your system.

Complete Code

import subprocess
import tempfile
import os

print("Hello World from Python!")

cpp_code = """
#include <iostream>
using namespace std;

int main() {
    cout << "Hello World from C++!" << endl;
    return 0;
}
"""

with tempfile.NamedTemporaryFile(delete=False, suffix=".cpp") as f:
    cpp_file = f.name
    f.write(cpp_code.encode())

exe_file = cpp_file.replace(".cpp", "")

compile_proc = subprocess.run(["g++", cpp_file, "-o", exe_file], capture_output=True, text=True)

if compile_proc.returncode != 0:
    print("C++ compilation failed!")
    print(compile_proc.stderr)
else:
    result = subprocess.run([exe_file], capture_output=True, text=True)
    print("Output from C++:")
    print(result.stdout.strip())

os.remove(cpp_file)
if os.path.exists(exe_file):
    os.remove(exe_file)

How It Works

  1. Python writes C++ code to a temporary file.
  2. g++ compiles the code into an executable.
  3. Python runs the executable and prints its output.
  4. Cleanup removes temporary files for a tidy finish.

Key Learnings

  • Use subprocess.run() to execute system commands from Python.
  • Create temporary files using tempfile safely.
  • Capture compiler output and program results.
  • Integrate Python and C++ seamlessly for automation or hybrid projects.

Further Experiments

  • Modify the C++ code dynamically (e.g., generate code from user input).
  • Run multiple C++ snippets from one Python script.
  • Measure execution time differences between Python and C++.
  • Use Python to benchmark or visualize C++ results.

With this simple integration, you’ve built a bridge between Python and C++, unlocking a world of hybrid programming possibilities. You can extend this example to dynamically generate more complex C++ programs, compile them on the fly, and benchmark their performance using Python scripts.