VB.NET。 如何将文本框输入或字符串转换为算术公式？

Question

I am trying to create a grading system where you can choose your own subject and components(recitation, quiz etc) and as well as customize the formula... I will be using ddl language to create the fields and tables in the database so all's well with that, however, I have a big problem with the formula... I do not know how I can convert the string formula (from the textbox or the database) containing "variable names" into a workable formula that the system will recognize.

short example.

I declare three integers a, b & c with corresponding values (a =1, b=2, c=3). then let the user input a formula in a textbox.

example: textbox1: a+c

then equate the results using b...

this is where the problem lies, the program reads it as plain string and does not recognize the variable DX

How will I do this?

Answer 1

Some libraries which can evaluate simple math expression strings in .NET are:

• Simple math explorer
• Fast Lightweight Expression Evaluator
• ILCalc
• MathExpressions library used in Calculator.NET
• NCalc
• This post describes the implementation of a dynamic formula calculator/evaluator in VB.NET. In case you want to implement something out of the ordinary, you could alter the provided code.

Hope I helped!