###This is an expression calculator which enables the users to naturally input expressions and define variables and functions.

• Author : Jingping Yu

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• Easy-plugin
• Supports handling with wrong expressions and generate corresponding warnings
• Supports user-defined functions and variables

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• From now on I will update the document in the online project and make sure it bounds with the codes. Currently you may refer to the docs bellow or have a glance at the codes.

####Setup and Installation

• Currently the project is still ongoing and due to the fact that I have never planned to make it a fully functional library (It is a homework only actually) the structure is in chaos. However, all you need to do is to #include "ExpressionParser.hpp" in your own project.

####Create an Expression

• In order to work as an expression calculator, an expression is definitely required. You may Create an expression by Expression *expression = new Expression ("5 * x + 7 x sin (SHIT (1, 11.24 ^ x))");

####Create a parser

• With your expression defined, you may create a parser by ExpressionParser *parser = new ExpressionParser (expression);

####Define variables

• As you can see there is an 'x' variable in the expression above. In order to make the parser know this, you need to call the method like this : parser->SetVariable ("x", 1.1);.

####Define Functions

• There is a "SHIT" function left undefined in the expression above. There is an AddNewFunction method in the ExpressionParser Class with three parameters : string func_name, int var_num, string expression. And you may define the function like this: parser->AddNewFunction ("SHIT", 2, "max (a + b) * sin (a / b)");.

####Calculating Results

• Now that you have given an expression and defined the variables and functions, the parser is ready to work now! Simply call parser->ParseExpression (); and the result would be stored in the parser. In order to get the result, please call Calculation *result = parser->GetResult ();. Please note that you are not getting a double value but rather a Calculation Result. There are three elements stored in a CalculationResult:

• Value : The actual result of the operation.
• IsValid : Is the operation actually valid.
• StatusInformation : The concise information about the operation. Whether the operations are manipulated well or some problems encountered.

• Here you may simply call double numericalResult = result->GetValue ();.

• I have to commit that currently the project is A PILE OF SHIT. It works, and works ONLY. I am working on the re-construct the essential codes to make it stronger and more stable.