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Posted 14 May 2012

Math Parser .NET C#

, 28 Feb 2014 GPL3
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This is light, fast and simple to understand mathematical parser designed in one class, which receives as input a mathematical expression (System.String) and returns the output value (System.Double)


This is light, fast and simple to understand mathematical parser designed in one class, which receives as input a mathematical expression (System.String) and returns the output value (System.Double). For example, if your input string is "√(625)+25*(3/3)" then parser returns double value — 50. 


The idea was to create a string calculator for educational goals.  

How it work   


For more please look at the code, I tried to explain the work of the parser in the comments and how it can be changed and extended.  

Convert to RPN:

* Input operators are replaced by the corresponding token (its necessary to distinguish unary from binary). 

Using the code  


public static void Main()
        MathParser parser = new MathParser();
    string s1 = "pi+5*5+5*3-5*5-5*3+1E1";
    string s2 = "sin(cos(tg(sh(ch(th(100))))))";
        bool isRadians = false;
        double d1 = parser.Parse(s1, isRadians);
    double d2 = parser.Parse(s2, isRadians);

        Console.WriteLine(d1); // 13.141592...
    Console.WriteLine(d2); // 0.0174524023974442


Ariphmetical operators :

  • () — parentheses;  
  • + —  plus (a + b); 
  • - — minus (a - b); 
  • * — multiplycation symbol (a * b); 
  • / — divide symbol (a / b); 
  • ^ — degree symbol (a ^ b).  

Functions :    

Trigonometric functions: 

  • sin(x);
  • cos(x);
  • tg(x);  
  • ctg(x). 

Hyperbolic functions:

  • sh(x);
  • ch(x);
  • th(x).  

Other functions: 
  • √(a), sqrt(a) — square root of a number; 
  • exp(x)  — exponential function (or just use e^x);  
  • (a)log(b) — logarithm; 
  • ln(x) — natural logarithm; 
  • abs(x) — absolute value.  


  • pi — 3.14159265...;  
  • e — 2.71828183....  

Arguments of the trigonometric functions can be expressed as radians (true) or degrees (false) by sending appropriate bool value to parse method. Example (as radians):   

parser.Parse("sin(90)", true);

Work with any char decimal separator in real number (regional settings).

New operators, functions and constants can be easily added to the code. 

This parser is simple (special designed in single class), convenient for the further implementation, expansion and modification.      

Points of Interest     

I better understand how parsers work and learned about the reverse-polish notation.


  • 2012/05/09: released the source code (1_0); 
  • 2012/06/07: optimized parser (1_2);    
  • 2014/02/28: rewritten version (1_4). 


This article, along with any associated source code and files, is licensed under The GNU General Public License (GPLv3)


About the Author

Kazakstan Kazakstan
My full name is Yerzhan Kalzhani. I’m a pragmatic software developer who loves tasks that are interesting and challenging. My motto in software developing: "Quality, Performance and Agile".

I prefer systematic approach when solving problem, so I think that every good developer first of all should be able to manage the complexity of a software system and produce the well-structured solution for a poor defined problem.

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Comments and Discussions

GeneralRe: Code Pin
kirnbas24-Aug-12 7:46
memberkirnbas24-Aug-12 7:46 
NewsSym Pin
Warren Harding16-Aug-12 20:32
memberWarren Harding16-Aug-12 20:32 
GeneralRe: Sym Pin
kirnbas24-Aug-12 6:19
memberkirnbas24-Aug-12 6:19 
QuestionBroken Image links Pin
Marcus Kramer7-Jun-12 4:53
memberMarcus Kramer7-Jun-12 4:53 
AnswerRe: Broken Image links Pin
kirnbas7-Jun-12 5:32
memberkirnbas7-Jun-12 5:32 
GeneralPlease show and explain the code Pin
PIEBALDconsult14-May-12 13:51
memberPIEBALDconsult14-May-12 13:51 
GeneralRe: Please show and explain the code Pin
kirnbas15-May-12 2:22
memberkirnbas15-May-12 2:22 
GeneralRe: Please show and explain the code Pin
PIEBALDconsult15-May-12 7:03
memberPIEBALDconsult15-May-12 7:03 
Very few people here will download code sight unseen. Especially if it's just to see how it's done. Show and explain the code and if someone wants to use it he may download it.
SuggestionQuite complicated expression evaluator... Pin
Andreas Gieriet14-May-12 12:18
memberAndreas Gieriet14-May-12 12:18 
QuestionYou might want to elaborate on some of the inner workings, etc. Pin
ednrg14-May-12 8:07
memberednrg14-May-12 8:07 

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