Microsoft C Runtime Here

The Microsoft C Runtime — A Story of Tools, Transition, and Trust

2. Historical Context & Evolution

• C99/C11 gaps – Missing tgmath.h, complex.h for many complex functions, aligned_alloc (added later), timespec_get, and full threads.h support.
• ABI & version hell – Different CRT versions (v100, v110, v120, v140, v142) incompatible with each other; mixing leads to crashes or heap corruption.
• Large binary overhead – Static linking (/MT) embeds a copy into every EXE; dynamic linking (/MD) requires distributing vcruntime140.dll.
• Licensing – Redistributable but requires proper deployment; older MSVCRT from Windows system folder cannot be used for new apps.
• Modern C++ friction – It's a C library; iostreams and std::string are separate, and mixing malloc with new without care causes trouble.
• No cross-platform friendliness – Not portable to Linux/macOS without Wine; _open vs open, _fseeki64 instead of fseeko.

Chapter 6 — Legacy and Future

Features of the Microsoft C Runtime

• Compiler support functions: exception handling, C++ new/delete, stack unwinding, typeid, thread-local storage (TLS), atexit.
• Entry point (mainCRTStartup, wmainCRTStartup).

By following these best practices and understanding the features and importance of the Microsoft C Runtime, developers can create efficient, reliable, and compatible applications that take advantage of the power of the MSVC compiler.