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GCC 13 (C++17) · free · no sign-up · input supported
Fast GCC builds for algorithms, data structures and systems practice.
Write, compile and run C++ online with GCC 13. The compiler panel shows warnings and errors with line numbers, and the program panel shows what your code printed.
Ideal for algorithm practice: paste a test case into the Input panel, read it with std::cin, and compare the result with the expected answer.
Structured bindings, std::optional, if constexpr and the full STL are available out of the box.
Both stages run in the sandbox; compiler diagnostics and program output are shown separately.
Everything in the Input panel is piped to standard input, so cin and getline behave as in a judge.
GCC 13 defaults to C++17 with GNU extensions. Most C++20 features also compile.
A run compiles a single translation unit. Keep declarations and definitions in the same file.
Check the Compiler panel first: if compilation fails, the program never runs. Also flush output with std::endl or '\n' before the program exits.
Each run has a few seconds of CPU time and a bounded memory budget; the process is killed and reported as a time-out otherwise.