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Online C++ Compiler

Write, run, and share code snippets — no setup required.

main.cpp
Output
Click Run to see the output here.

Compile and run C++ online in your browser

This is a free online C++ playground and compiler. Write C++ code directly in your browser, hit Run, and watch g++ compile and execute your program in seconds — no MSVC, no CMake, no Visual Studio required. It's the fastest way to test an STL container, try a template trick, or solve an interview problem.

Under the hood, the editor uses the same engine as VS Code (C++ syntax highlighting, header autocompletion, diagnostic squiggles), and your code compiles with g++ on Alpine Linux with the full C++ STL available — <vector>, <map>, <unordered_map>, <algorithm>, <memory>, <thread>. Whether you're exploring smart pointers, testing a lambda, or prepping for a C++ interview, this online C++ compiler goes from idea to output in seconds.

What makes this C++ playground useful

  • Instant C++ compilation — write code, press Run, and see output from the online g++ compiler in seconds, no CMake or Visual Studio needed.
  • Full C++ syntax highlighting, header autocompletion, and clear g++ compile errors — the same editor engine that powers VS Code.
  • Stdin input supported — std::cin >> x, std::getline(std::cin, line), and scanf all read from the playground's input box, so competitive-programming patterns and interview problems work end-to-end. No install — no g++, clang, MSVC, or CMake.
  • g++ compiler with the full C++ STL — use vector, map, unordered_map, algorithm, and modern C++ features without setting up a toolchain.

What you can build in the C++ playground

  • STL containers — vector, map, unordered_map, set — plus <algorithm> (sort, transform, accumulate) the classic interview toolkit.
  • Data structures by hand — linked lists, binary trees, hash maps — plus classic algorithms (BFS, DFS, dynamic programming) with modern C++17 syntax.
  • Quick C++ experiments — test a lambda, benchmark a sort, try auto type deduction, or confirm a pointer arithmetic trick without a CMake project.

Online C++ compiler FAQ

Is the online C++ compiler free?
Yes. The online C++ playground is completely free — no sign-up, no MSVC, no g++ to install, no CMake to configure. Open the page and compile.
Do I need g++ or a C++ compiler installed?
No install needed. You don't need g++, clang, or MSVC on your machine — the online C++ compiler compiles your code with g++ on Alpine Linux and runs it in seconds.
Does the C++ playground work on mobile and Chromebooks?
Yes. The C++ playground runs on any modern browser — desktop, tablet, or mobile. Great for running C++ from a Chromebook or a machine where you can't install a compiler.
Does the C++ playground support std::cin and stdin?
Yes. The playground has a stdin input box — std::cin >> n;, std::getline(std::cin, line);, and scanf all read your typed lines the same way they would when you run ./a.out locally. Ideal for competitive-programming problems, Codeforces-style inputs, and interview questions.
How do I learn C++ after trying the playground?
Edit the sample C++ code, press Run, and iterate. When you want structured practice, Coddy's interactive C++ course covers pointers, STL containers, templates, and modern C++ features.