Inverse Polish algorithm to implement a arithmetic calculator

The calculator is implemented in two steps:

1. The regular expression (infix expression) is processed into a suffix expression.

2. Computes a suffix expression.

The first step: infix such as: 1+ (2*3)-4/2, converted to suffix 123*+42/-.

Rule: From left to right traversal infix expression, if it is a number, directly out, if it is a symbol, then the priority, if the current symbol (including the right parenthesis) priority is not higher than the top of the stack, then out of the stack, until the priority is not satisfied (if the right parenthesis, Then until the left parenthesis is out of the stack, the suffix expression does not need the left and right brackets, and then the symbol is put into the stack. High-priority direct entry stack. So until it's done.

Step two: Calculate the suffix expression.

Rule: The suffix expression is traversed from left to right, if it is a number, directly into the stack, if it is a symbol, then pop up the top of the stack of two numbers, and this symbolic operation. The result of the operation is then stacked. Until the end of the calculation.

Inverse Polish algorithm to implement a arithmetic calculator