Following a blog post, fixed in python2: Debugger speedups using cython not found.

The same problem was found in python3.5, where the original python required a VC++ Compiler for the installation (MInGW is also available, and it is generally not recommended to use PIP to install some third-party python libraries, and many extensions written in C required a VC++ Compiler for the installation, otherwise “error: command ‘cl.exe’ failed:” would occur. The most common compiler is Visual Studio C ++.

Compiler VS2008 C++ compiler is required in Python2.7, whereas python3 to 3.4 is compiled using VS2010, and python3.5 is compiled using VS2015.
However, as anyone who has ever installed a bloated IDE like VS knows, it comes bundled with a bunch of Microsoft plug-ins, takes up a lot of C disk space, and starts slowly.
if the computer is configured in a general way, the computer will be very stuck, and generally there is no need to install the entire VS.

For Python 2.7, Microsoft has released the Microsoft Visual C++ Compiler for Python 2.7 directly for download and installation.
http://www.microsoft.com/en-us/download/details.aspx?id=44266

For python3.5 you will need to install the Visual C++ Build Tools compiler provided by Microsoft
Download address: http://landinghub.visualstudio.com/visual-cpp-build-tools
to install, remember to choose Windows SDK 8.1 and 10 SDK, so don’t pack VS2015 can also compiled a package of C code in the PIP.

following a blog post resolved in python2: Debugger speedups using cython not found.

was found to have the same problem in python3.5. The original python required VC++ Compiler to compile and install (MInGW can also be used, is generally not recommended, is generally not recommended to use PIP to install some third-party python libraries under Windows, many use C to write some extensions, and need VC++ Compiler to compile and install, otherwise “error: The command ‘cl. Exe’ failed: “. The most common compiler for is Visual Studio C ++.

like Python2.7 requires VS2008 C++ compiler, whereas python3 to 3.4 is compiled in VS2010, and python3.5 is compiled in VS2015.

however, anyone who has ever installed VS this huge bloated IDE knows that it comes bundled with a bunch of Microsoft plug-ins, takes up a lot of C disk space, and starts slowly,
if the computer configuration is general, the computer will be very stuck, generally do not do related development, there is no need to install the whole VS.

for Python 2.7, the Microsoft Visual C++ Compiler for Python 2.7 is available for download and installation.
http://www.microsoft.com/en-us/download/details.aspx?id=44266

for python3.5 the compiler provided by Microsoft is installed – Visual C++ Build Tools

Download address:

http://landinghub.visualstudio.com/visual-cpp-build-tools
to install, remember to choose the Windows SDK 8.1 and Windows SDK 10 , so don’t pack VS2015 can also compiled a package of C code in the PIP.