eval

Is there any way to parse a string in vb.net (like, built in methods), that can do math like Eval can? For example, 3+(7/3.5) as a string would return 2. I am not asking for you to code this for me, I just want to know if there is a built in way to do this, if there is not I will code it myself. I can wager that it would not be able to parse stuff like Sin(90) on its own, and I understand that would need to be replaced by Math.Sin(90). If there is a built in method, how do you use it? Ahmad Mageed There's a shortcut for limited (ie. simple) math expressions by using the DataTable.Compute

Possible Duplicate: When is JavaScript’s eval() not evil? I am writing a script in which users have to write in a currency amount, some examples could be (user input >> converts to), with USD as default currency: 50 >> 50.0 USD 50.5 >> 50.5 USD 50+1 USD >> 51.0 USD 50 GBP >> 50.0 GBP I want to make this as smooth as possible, therefore I want to use JavaScript (it's a web app based on PHP/MySql + JavaScript). I want to use regex to filter the input, run it through eval() and return it. Is this a bad idea? I've read some topics about eval() being a security issue. I just don't see how. A user

JSinDeep1: 探索执行环境 (Execution Context)-ES3 篇 声明 JSinDeep 系列文章主要内容为作者对 ECMA-262 标准 中一些概念的理解和探究，同时意在帮助大家快速理解。本着严谨的态度，同时又需避免 API 式的枯燥细节罗列。文章会以适当插图、例子去诠释概念，致力于通俗易懂。更具体、严谨、完整的描述建议阅读 ECMA262 文档。碍于作者水平有限，文中若有错误，欢迎大家批评指正。 *其它版本: English-Blog , English-PDF , Chinese-Blog , Chinese-PDF 概要 在我们写JavaScript代码时会定义一些变量、函数等。解释器在执行这些代码时是如何处理并找到我们定义的这些数据的？在程序执行时，引用这些变量等操作的背后都发生了什么？本文主要探讨 ECMA-262-3 标准 中的执行环境 (Execution Context) 及与之相关的一些内部机制和模型。 定义 当程序执行的控制权转移至ECMAScript可执行代码时，会进入到一个执行环境中 （Execution Context，缩写为EC） 。在一个EC内也可能进入到一个新的EC，这些EC逻辑上 1 会形成一个栈 (Stack) 。 EC 是程序运行时动态创建的。例如：每一个函数在被调用时都会创建一个EC，重复调用函数 （包含递归调用的情形

Reason 1. provide more thorough error checking 2. avoid error-prone constructs 3. clarifies many ambiguities in the 3rd edition specification 4. others make ECMAScript code more robust Common ways 1. strict script // before any code "use strict" ; var v = "I'm a strict code" ; 2. strict function function foo() { "use strict" ; return "I'm a strict function" ; } Changes 1. impossible to accidentally create global variables "use strict" ; mistypedVariable = 1; // throws a ReferenceError 2. makes assignments which would otherwise silently fail throw an exception "use strict" ; NaN = true ; //

引发了最近对eval火爆的讨论，刚好之前也做过类似的测试，我也跟风凑个热闹，提供两组数据供大家参考。 测试环境： a. 机器：Intel(R) Corei7-2720 2.2Ghz （4核心8线程）、内存8Gb b. OS：Windows 7 Enterprise SP1 64-bit c. 浏览器： b.1 Google Chrome 21.0.1180.79 m b.2 Firefox 14.0.1 b.3 IE9.0.8112.16421 d. 测试方法 d.1 每个用例测试5次，耗时取最小值。 d.2 测试过程中 没有 开启Firebug或Chrome Console，开启这些工具会使时间倍增，很难在有效时间内得到该用例结果 用例A1： 我们在内联函数中调用空的eval("") ! function () { var a = 1, b = 2, c = true ; function func() { var d = 2; e = !c; eval(""); } for ( var i = 0; i < 2999999; i++) { func(i, i + 1, i + 2); } }(); 用例A2： 注释掉内联函数中的eval("") !function() { var a = 1 , b = 2 , c = true ; function func() { var

" Is 'eval' supposed to be nasty? " inspired this one: Mostly everybody agrees that eval is bad, and in most cases there is more elegant/safer replacement. So I wanted to ask: if eval is misused that often, is it really needed as a language feature? Is it doing more evil than good? Personally, the only place I find it useful is to interpolate strings provided in config file. Edit: The intention of this question is to get as many real-life cases as possible when eval is the only or the best solution. So please, don't go into "should a language limit a programmer's creativity" direction. Edit2: