expressionEvaluator.cpp

// include statements
#include <iostream>
#include <math.h>

// using statements
using std::cout;
using std::endl;

// input char arrahandleExponent
char* expression = (char*)"(2+2*(3-6)-1)/2.5";

// function prototypes
float handleParenthesi();


// Handle exponents
float handleExponent(float currentValue = handleParenthesi()) {
	if (*expression == '^') {
		expression++;
		return handleExponent(pow(currentValue, handleParenthesi()));
	}
	else {
		return currentValue;
	}
}

// Handle division and multiplication
float handleMultiplication(float currentValue = handleExponent()) {
	if (*expression == '/' || *expression == '*') {
		if (*(++expression - 1) == '/') {
			return handleMultiplication(currentValue / handleExponent());
		}
		else {
			return handleMultiplication(currentValue * handleExponent());
		}
	}
	else {
		return currentValue;
	}
}

// Handle addition and subtraction
float handleAddition(float currentValue = handleMultiplication()) {
	if (*expression == '-' || *expression == '+') {
		if (*(++expression - 1) == '-') {
			return handleAddition(currentValue - handleMultiplication());
		}
		else {
			return handleAddition(currentValue + handleMultiplication());
		}
	}
	else {
		return currentValue;
	}
}

// Handle parenthesis
float handleParenthesi() {
	float result;
	if (*expression == '(') {
		expression++;
		result = handleAddition();
		expression++;
		return result;
	}
	else {
		return strtof(expression, &expression);
	}
}

int main()
{
	cout << handleAddition() << endl;
}