用c++语言借用栈将中缀表达式转化为后缀表达式并且计算出后缀表达式的值，支持浮点数运算-Borrowing the language used c++ stack will infix expressions into postfix expression and calculate the value of the postfix expression of support for floating-point operations

The primary aim of this book is to help the reader understand how the facilities offered by C++ support key programming techniques. The aim is to take the reader far beyond the point where he or she gets code running primarily by copying examples