error C2039: 'memchr' : is not a member of '`global namespace''

It was a stupid mistake! I have a file called "String.h" in a library project which is being picked up by the <cstring> header. Probably because I have added the path to <String.h> as an additional include directory in my test project (where I am getting this error.)

这个错误还主要是我调用了一个Utils的辅助库，Utils里面有一个头文件叫 String.h, 包含这个String.h的时候应该是编译器把它当成VC库里的那个 string.h了，因为VC对文件名字是不区分大小写的，所以编译时才导致这个错误。

           最好的解决办法，就是把Utils库里的文件 String.h给改名字，这样问题就彻底根除了。