接收“错误C2011:‘TextureManager’:‘类’类型重新定义”错误。在文件中定义#endif。

I am following the book "SDL Game Development By Shaun Mitchell" to learn SDL2 and have run into a compiler error I cannot solve. I am receiving a "error C2011: 'TextureManager' : 'class' type redefinition" when attempting to build the project. I am using Visual Studio 2008. I have added the precompile commands as typically suggested for this error. I have cleaned the project then built it. The error continues every time I attempt to build the project. I am following the book "SDL Game Development B