Postfix to infix with unary/binary operators

梦想的初衷 提交于 2019-12-08 06:29:58
问题 I am trying to make a converter from postfix to infix notation and need some help. There is already a question about infix-to-postfix conversion, which gives an example I am failing to convert back. (Note: a minus sign is missing there!) The following is the output of my converter, where the 1st "column" is postfix input, the 2nd is my infix output, and the 3rd is what I probably should get(?): 2 - = - 2 =? - 2 true 1 + 2 + = + 1 + 2 =? + 1 + 2 true 1 + 2 + + = + (+ 1 + 2) =? + 1 + + 2 false

Shunting-yard algorithm in c++

﹥>﹥吖頭↗ 提交于 2019-12-06 01:48:57
I need a function that takes an infix string (like "3 + 4 * 9"), and convert it to postfix (like "4 9 * 3 +"). I got it working until you throw in parentheses within parentheses. I've been working on it all day and can't figure out what I'm doing wrong- can someone with a fresh mind see it, maybe? I

Arithmetic Expression Evaluation using Reverse Polish Notation (RPN)

风格不统一 提交于 2019-12-05 17:30:28
A mathematical expression is usually expressed in infix notation. For evaluation purposes, we can change it to postfix (reverse polish) notation (using algorithms like Shunting-Yard ) and then evaluate the postfix notation using stack. I found out that calculators use this technique, but do today's

Parse Math Expression in PHP

[亡魂溺海] 提交于 2019-12-04 22:55:06
I'm currently trying to parse math expression into expression tree. But I'm stuck on the stage where I need to implement functions and negates. I don't understand logic to do it using Shunting-Yard algorithm. What I currently want to do is to support Negates, like -(x+5) Function calls, like min(x,y

Shunting-Yard VS Recursive Descent Parser

人盡茶涼 提交于 2019-12-04 04:48:56
问题 I am building an advanced mathematical parser and would like to know the difference between Shunting-Yard and the other available parser algorithms like "Descent Parser" knowing that I prefer to store the formula in RPN notation. Thanks in advance, 回答1: I've never had much use for the "shunting yard" algorithm because it seems focused on just infix expressions. Recursive descent parsing easily does expressions and most of what you want to do with more complex parsers. Being more general, I

Trouble understanding what to do with output of shunting-yard algorithm

蹲街弑〆低调 提交于 2019-12-03 00:39:21
I've been looking at the wiki page: I've used the code example to build the first part, basically I can currently turn : 3 + 4 * 2 / ( 1 - 5 ) ^ 2 ^ 3 into 3 4 2 * 1 5 − 2 3 ^ ^ / + But I don't know how to then use 3 4 2 * 1 5 − 2 3 ^ ^ / + to

Java Expression Parser & Calculator Shunting Yard Algorithm

房东的猫 提交于 2019-12-02 06:58:44
问题 So the task is to create our own parser for a expression calculator. For Example: Input: 3+2*1-6/3 Output: 3 Input: 3++2 Output: Invalid Expression Input: -5+2 Output: -3 Input: 5--2 Output: 7 The code here solves a part of the problem except that it has a fixed input and negative values cannot be solved, And I'm not quite sure yet if it really does solve the expression with operator precedence. but I already modified it to get an input expression from the user. and I've been wondering for

Tokenizing an infix string in Java

醉酒当歌 提交于 2019-11-30 17:20:23
问题 I'm implementing the Shunting Yard Algorithm in Java, as a side project to my AP Computer Science class. I've implemented a simple one in Javascript, with only basic arithmetic expressions (addition, subtraction, multiplication, division, exponentiation). To split that into an array, what I did was find each of the operators ( +-*/^ ), as well as numbers and parentheses, and I put a space around them, and then I split it into an array. For example, the infix string 4+(3+2) would be made into