calcoloespressionealgebrica

#include <iostream>
#include <string.h>
#include "evaluate.h"

using namespace std;

bool isAnOperator(char c){
    if( (int(c) >= 42) && (int(c) <= 47) )
        return true;
    return false;
}

void sizeStacks(string expression, int operatorStackSize = 0, int numberStackSize = 0){
    int exprLenght = expression.size();
    for( int i=0; i < exprLenght; i++ ){
        if( isAnOperator(expression[i]) )
            operatorStackSize++;
        else if( expression[i] == '(' || expression[i] == ')' ){
            //do nothing
        }
        else numberStackSize++;
    }
}

int evaluateExpression(string expression){
    int opStSize = 0, numStSize = 0, result;
    int exprLenght = expression.size();
    sizeStacks(expression, opStSize, numStSize);
    Stack<char> operatorStack(opStSize);
    Stack<int> numberStack(numStSize);

    for(int i=0; i < exprLenght; i++){
        if( isAnOperator(expression[i]) )
            operatorStack.push(expression[i]);
        else if( expression[i] == '(' ){
            i++;
            string bracketExpr;
            while( expression[i] != ')' )
                bracketExpr += expression[i++];
            bracketExpr = '\0';
            numberStack.push(evaluateExpression(bracketExpr));
        }
        else numberStack.push(expression[i]);
    }

    int num1Popped, num2Popped;
    char operatorPopped;
    while( !operatorStack.isEmpty() ){
        numberStack.pop(num1Popped);
        numberStack.pop(num2Popped);
        operatorStack.pop(operatorPopped);
        switch(operatorPopped){
        case '+':
            numberStack.push(num1Popped+num2Popped);
            break;
        case '-':
            numberStack.push(num1Popped-num2Popped);
            break;
        case '*':
            numberStack.push(num1Popped*num2Popped);
            break;
        case '/':
            numberStack.push(num1Popped/num2Popped);
            break;
        }
    }
    return numberStack.pop(result);
}