Run C++ 26 online

What's in C++ 26

• Static reflection (P2996) — compile-time inspection of the type system.
• Contracts (P2900) — pre/post conditions checked at build or runtime.
• Executors (P2300) — a standard vocabulary for asynchronous work.

What you get in C++ 26

Clicking "Run now" opens the playground with this exact code and a matching test case — passes on first Run.

#include<iostream>
int main(){int n;std::cin>>n;std::cout<<n*2<<std::endl;return 0;}

How ls-judge runs C++ 26

Every submission is compiled and executed inside its own Firecracker microVM — the same isolation primitive AWS Lambda uses. No shared container, no shared kernel with other users' code. The C++ 26toolchain shipped with the microVM is the real thing (not a browser-side emulation): syscalls behave the way they do in production, and the compile / runtime behaviour matches what you would see on your own machine with that version installed.

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