DOS下的科学计算器，主要是通过把表达式转换为逆波兰式，再利用堆栈递归求解；-Under DOS scientific calculator, mainly through the expression is converted to Reverse Polish-style, and then use recursion to solve the stack

简单的计算器，能实现简单表达式的计算，采用堆栈实现，对堆栈学习很有用-Simple calculator, simple expressions can be calculated, using the stack implementation is useful for studying the stack

一般的计算器最多算到16位，这个可以算到堆栈溢出为止，试试吧-Large number calculator, calculator generally count up to 16, this can be considered to stack overflows, try it