Some are compile-only to let you check whether your code is legal, and some let you also run your test programs to see their output. Or try one of these online compiler pages, which offer a range of compilers including the latest from Clang, GCC, Intel, and Microsoft.

IBM XL C/C++ Compiler: A Clang-based Community Edition is available for Linux on Power, free for production use.Oracle Solaris Studio C++ Compiler : A C++ compiler for Solaris and some distributions of Linux, free for all commercial and non-commercial use.Embarcadero: A free Clang-based C++ compiler by Embarcadero.Visual C++ 2017 Community: A free Windows C++ compiler by Microsoft.Clang: A new open-source C++ compiler for various platforms.A build for Windows is available here, builds for other platforms are likely available via your platform's package manager, or you can build it yourself using instructions here. Gnu Compiler Collection: Includes g++, a popular C++ compiler.

There are good free C++ compilers available for all major OS platforms.

Online msvc compiler