利用栈来实现表达式的计算（+ -* /）

======================================================================== CONSOLE APPLICATION : Expression ======================================================================== AppWizard has created this Expression application for you. This file contains a summary of what you will find in each of the files that make up your Expression application. Expression.dsp This file (the project file) contains information at the project level and is used to build a single project or subproject. Other users can share the project (.dsp) file, but they should export the makefiles locally. Expression.cpp This is the main application source file. ///////////////////////////////////////////////////////////////////////////// Other standard files: StdAfx.h, StdAfx.cpp These files are used to build a precompiled header (PCH) file named Expression.pch and a precompiled types file named StdAfx.obj. ///////////////////////////////////////////////////////////////////////////// Other notes: AppWizard uses "TODO:" to indicate parts of the source code you should add to or customize. /////////////////////////////////////////////////////////////////////////////