expression-evaluator

Small learning project, that permiss you evaluate simple mathematical expressions.

Syntax rules:

• Numbers

Fractional part must be separated with dot ( . ) not comma ( , ). If number integer part equals 0 it can be skipped.

Next two numbers are equal: 0.15 = .15

Unary plus and minus must be placed in front of number without spaces, like this: -3

• Operations

Evaluator support five operations: addition(+), subtraction(-), division(/), multiply(*), power(^) with correspond priorities.

Priority of operations can be changed with brackets.

Unary plus and minus before brackets can placed with spaces, like this: - (12 + 3). Its will not an error.

Usage in code

You can use function evaluate() defined in header Evaluator.hpp. It takes expression string and return instance of struct EvaluateResult where field success indicates was expression successfuly evaluated or not. If it was, result stored in field value.

Or if you want somehow change evaluation process, you must follow next pattern.

• First you have to split string into tokens with function getTokens().
• Next you need call function simplifyTokens() with tokens youve got.
• After that call function verifyTokens() to verify correctness of expression.
• And finally if verifyTokens() return true call function evaluateTokens() that return result of evaluation.