这说我精心收藏的一个求表达式值的5种方法源代码，对学习数据结构的人可能会有帮助！-It said that I carefully seek the expression of a collection of five kinds of methods the value of source code, data structure for learning may be helpful!

使用键盘输入表达式，计算表达式的值并输出；将表达式转化成后缀表达式输出，利用后缀表达式求表达式的值并输出。-Keyboard input expression, the expression values calculated and output the expression into postfix expression output, the use of a postfix expression to uate the expression and output.

表达式求值，用户输入需要计算的计算式，程序计算出来。-Expression for the value of user input required calculation calculation formula, the program calculated.