Calculator

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#include "calculator.h"
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QString Calculator::calcAll(QString all){
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    all = deleteUnnecessary(all);
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    all = seekDevideMulti(all);
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    all = seekMinusPlus(all);
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    all = rounding(all);
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    return all;
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}
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QString Calculator::deleteUnnecessary(QString all){
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    if(all == "-") return "0";
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    while(!isdigit(QString(all).toStdString()[all.size()-1])){
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        all.remove(all.size()-1,1);
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    }
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    return all;
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}
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QString Calculator::plus(QString firstNum, QString secondNum){
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    double res = firstNum.toDouble() + secondNum.toDouble();
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    return QString::number(res, 'g', 31);
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}
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QString Calculator::minus(QString firstNum, QString secondNum){
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    double res = firstNum.toDouble() - secondNum.toDouble();
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    return QString::number(res, 'g', 31);
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}
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QString Calculator::multi(QString firstNum, QString secondNum){
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    double res = firstNum.toDouble() * secondNum.toDouble();
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    return QString::number(res, 'g', 31);
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}
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QString Calculator::devide(QString firstNum, QString secondNum){
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    double res = firstNum.toDouble() / secondNum.toDouble();
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    if(secondNum.toDouble() == 0)
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        res = 0;
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    return QString::number(res, 'g', 31);
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}
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QString Calculator::doOperation(QString firstNum,QString op, QString secondNum){
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    if(op == "+") return plus(firstNum, secondNum);
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    else if(op == "-") return minus(firstNum, secondNum);
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    else if(op == "/") return devide(firstNum, secondNum);
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    else if(op == "x") return multi(firstNum, secondNum);
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    return 0;
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}
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QString Calculator::seekDevideMulti(QString all){
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    QRegExp rx_d("([\\-]?\\d+\\.?\\d*)[\\/]([\\-]?\\d+\\.?\\d*)");
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    QRegExp rx_multi("([\\-]?\\d+\\.?\\d*)[x]([\\-]?\\d+\\.?\\d*)");
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    return countPath(all ,rx_multi, rx_d, "x", "/");
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}
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QString Calculator::seekMinusPlus(QString all){
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    QRegExp rx_m("([\\-]?\\d+\\.?\\d*)[\\-]([\\-]?\\d+\\.?\\d*)");
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    QRegExp rx_p("([\\-]?\\d+\\.?\\d*)[\\+]([\\-]?\\d+\\.?\\d*)");
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    return countPath(all ,rx_m, rx_p, "-", "+");
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}
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QString Calculator::countPath(QString all, QRegExp rxOne, QRegExp rxTwo, QString opOne, QString opTwo){
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    int id;
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    QString res;
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    QString firstNum,secondNum;
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    while(rxOne.indexIn(all) != -1 || rxTwo.indexIn(all) != -1){
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        if(rxTwo.indexIn(all) == -1 || (rxOne.indexIn(all)<rxTwo.indexIn(all) && rxOne.indexIn(all) != -1)){
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            firstNum = rxOne.cap(1);
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            secondNum = rxOne.cap(2);
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            id = rxOne.indexIn(all);
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            res = doOperation(firstNum, opOne, secondNum);
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        }
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        else{
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            firstNum = rxTwo.cap(1);
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            secondNum = rxTwo.cap(2);
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            id = rxTwo.indexIn(all);
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            res = doOperation(firstNum, opTwo, secondNum);
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        }
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        all.replace(id, firstNum.size() + secondNum.size()+1, res);
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    }
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    return all;
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}
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QString Calculator::rounding(QString all){
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    QRegExp rx_point("([\\-]?\\d+\\.\\d)(\\d)(\\d)");
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    if(rx_point.indexIn(all) >= 0){
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        QString delta;
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        if(rx_point.cap(3).toDouble() >= 5){
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           delta = "1";
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        }
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        else {delta = "0";}
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        all = rx_point.cap(1) + plus(rx_point.cap(2), delta);
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    }
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    if (all.toDouble() == 0) return "0";
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    return all;
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}
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