什么是VC运行库？ 下面是一个来自stackoverflow的回答，我觉得很有道理：
https://stackoverflow.com/questions/4209684/ms-visual-c-runtime-library-what-for
The MSVCRT is a set of DLLs that implements parts of the C++ language. Functions like printf, memcpy and the like are implemented in these DLLs.
Every program that is compiled with a particular compiler and dynamically linked to the C++ runtimes must somehow have the correct version of the CRT binaries on the target machine. As a result, applications that ship to end users are often (usually?) also shipped with a package of these DLLs. This package is called a "redistributable" (or "redist"), and there is a different one for every combination of exact compiler version and target platform. For example, there are seperate and distinct redists for each of the following:
- MSVC 10, 64-bit windows
- MSVC 10, 32-bit windows
- MSVC9, 64-bit windows
- MSVC9 SP1, 64-bit windows
et cetera.
Yes, Windows usually "comes with" some version of the CRT. However, it comes with the version(s) that it needs in order to run the apps that shipped with Windows. If Windows and all it's apps were compiled in MSVC8 SP2 and your app is compiled in MSVC10, the CRT you require won't be present on the box simply because it's running Windows.
This is why its common practice to ship apps along with redists.
EDIT:
By way of Houdini like magic, I predict your next question will be "where do I get the redists?"
The answer is, from MicroSoft. Try a google search for "msvc 9 x64 redist" and you will find:
