evaluate

Is there a method that allows me to evaluate a mathematical expression in a string? Example (Not actual Code): Input = "2+2" Output = SomeMethod(Input) Output = 4 Update: Nevermind, I found a way around it by using DataTable.Compute. You'll need a math expression parser to handle this. Here are some various open source options on CodePlex: Simple Math Parser Fast Lightweight Expression Evaluator ILCalc A search will find many others... 来源： https://stackoverflow.com/questions/6604840/vb-net-evaluating-mathematical-expression-in-a-string

I'm looking for a relatively simpler (when compared with writing a parser) way to evaluate boolean expressions in Java, and I do not want to use the JEP library. I have a String expression like: (x > 4 || x < 8 && p > 6) and my aim is to replace the variables with values. Is there a way by which I can evaluate this expression? Bear in mind that this can be any level deep so writing a parser would be very complex. basszero You could use the scripting engine in Java6 and the choose any of the popular scripting languages like Scala , Ruby , Python , Groovy , and Javascript . Than all you have to

Say I have a string, $char. $char == "*". I also have two variables, $a and $b, which equal "4" and "5" respectively. How do I get the result of $a $char $b, ie 4 * 5 ? Thanks :) You can use eval() as suggested by @konforce, however the safest route would be something like: $left = (int)$a; $right = (int)$b; $result = 0; switch($char){ case "*": $result = $left * $right; break; case "+"; $result = $left + $right; break; // etc } safest method is a switch construct: function my_operator($a, $b, $char) { switch($char) { case '=': return $a = $b; case '*': return $a * $b; case '+': return $a + $b

Okay lets say I have a string such as this in a text file: ((( var1 AND var2 AND var3) OR var4) AND ((var5 OR var6) AND var7)) after parsing this into the c program and the vars are handled and set correctly it will end up looking something like this: ((( 1 AND 0 AND 0) OR 1) AND ((0 OR 1) AND 1)) Are there any useful libraries out there for evaluating expressions that are represented as one string like this? I was thinking I could just call a perl program with the string as an argument that would be able to return the result easily but wasn't sure if there was a library in C that did this, or

I'm trying to pass a variable into a page.evaluate() function in Puppeteer , but when I use the following very simplified example, the variable evalVar is undefined. I'm new to Puppeteer and can't find any examples to build on, so I need help passing that variable into the page.evaluate() function so I can use it inside. const puppeteer = require('puppeteer'); (async() => { const browser = await puppeteer.launch({headless: false}); const page = await browser.newPage(); const evalVar = 'WHUT??'; try { await page.goto('https://www.google.com.au'); await page.waitForSelector('#fbar'); const links