打开"VS2013开发人员命令提示后"，上面提示"cannot determine the location of the vs common tools folder"，于是打开VC/bin目录下的vcvars32.bat，发现没有找到环境变量VS120COMNTOOLS。但是，我明明添加了VS120COMNTOOLS这个环境变量。为什么VS识别不出VS120COMNTOOLS？
解决方法：添加PATH环境变量，值为：C:WindowsSystem32
原文：he problem is that the bat uses de reg command and it searches that in the PATH system variable. Somehow you have managed to get "C:WindowsSystem32" out of the PATH variable, so just go to the system variables (right click "My Computer"
> "Properties" > advanced config > "Environment Variables", search the PATH variable and add at the end separated by ";" :
C:WindowsSystem32