How to calculate using formulas?

Question

C++ / C#

I have a textbox where the formula is entered, but how to make the calculation take place in it, I don’t know how this can be done ??

Answer 1

You can use ready-made libraries.
For example, MathNet.Symbolics
The library is written in F#, but you can also use it in a C# project:
Math-NET-Symbolics-with-C-VB-NET-and-C-CLI
As you can see from the example:

using MathNet.Symbolics;
using Expr = MathNet.Symbolics.SymbolicExpression;
...
Expr.Parse("1/(a*b");  // выбросит исключение
Expr.Parse("1/(a*b)").ToString(); // вернет строку "1/(a*b)"

The API is quite convenient.
Simple functions/formulas shouldn't be a problem. If there are not enough opportunities or you find a bug - open an issue (in English) or even a PR - the maintainer accepts them without problems.
And I, in turn, as one of the contributors, will be happy to answer any questions or help with the implementation of the functionality.
There are other libraries, some of which surpass MathNet.Symbolics in terms of capabilities, but since I have not worked with them, I cannot recommend it.

Answer 2

Look at https://github.com/pieterderycke/Jace