将变量放在标题中的位置？

Question

我需要能够从wager.cpp访问在mainwindow.h中声明的QList<QRadioButton *> colorList colorList。

我将在这里展示我目前的尝试。

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H


#include <QMainWindow>
#include <QPushButton>
#include <QTextEdit>
#include <QCheckBox>
#include <Qlist>
#include <QRadioButton>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);



    ~MainWindow();

private slots:
    void runButtonClicked();

private:
    Ui::MainWindow *ui;
    QPushButton *runButton;
        QTextEdit * runText;

    };

 QList<QRadioButton *> colorList; // where should i put this??


    #endif // MAINWINDOW_H

错误：LNK2005：“class QList colorList”（？colorList @@ 3V？$ QList @ PAVQRadioButton @@@@ A）已在main.obj中定义

wager.cpp

#include "wager.h"
#include "mainwindow.h"
#include "deck.h"

Wager::Wager()
{
}

void build_bet_lists()

{
for(int i=0;i<5;i++)
    {
        qDebug()<<colorList[i]->isChecked;

}
}

colorList的定义是

mainwindow.cpp

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)

{

QRadioButton * street1BetBlack = new QRadioButton("Black");
QRadioButton * street2BetBlack = new QRadioButton("Black");
QRadioButton * street3BetBlack = new QRadioButton("Black");
QRadioButton * street4BetBlack = new QRadioButton("Black");
QRadioButton * street5BetBlack = new QRadioButton("Black");

QRadioButton * street1BetRed = new QRadioButton("Red");
QRadioButton * street2BetRed = new QRadioButton("Red");
QRadioButton * street3BetRed = new QRadioButton("Red");
QRadioButton * street4BetRed = new QRadioButton("Red");
QRadioButton * street5BetRed = new QRadioButton("Red");

QList<QRadioButton *> colorList;
colorList << street1BetBlack << street1BetRed << street2BetBlack << street2BetRed << street3BetBlack << street3BetRed << street4BetBlack << street4BetRed << street5BetBlack << street5BetRed ;

}

Answer 1

像你一样在标题中声明它：但声明它为extern ：

extern QList<QRadioButton *> colorList; //declared

除了在标题中“声明”它之外，还要在CPP文件中“定义”它：

QList<QRadioButton *> colorList; //defined

在全局范围内定义它，而不是在MainWindow构造函数中定义它：

QList<QRadioButton *> colorList;

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)

{


QRadioButton * street1BetBlack = new QRadioButton("Black");
QRadioButton * street2BetBlack = new QRadioButton("Black");
QRadioButton * street3BetBlack = new QRadioButton("Black");
QRadioButton * street4BetBlack = new QRadioButton("Black");
QRadioButton * street5BetBlack = new QRadioButton("Black");

QRadioButton * street1BetRed = new QRadioButton("Red");
QRadioButton * street2BetRed = new QRadioButton("Red");
QRadioButton * street3BetRed = new QRadioButton("Red");
QRadioButton * street4BetRed = new QRadioButton("Red");
QRadioButton * street5BetRed = new QRadioButton("Red");

colorList << street1BetBlack << street1BetRed << street2BetBlack << street2BetRed << street3BetBlack << street3BetRed << street4BetBlack << street4BetRed << street5BetBlack << street5BetRed ;


}

或者，您可以将其声明并定义为类MainWindow的静态成员。

Answer 2

您必须使用extern关键字来访问C ++中的全局变量。 语法如下：

extern type varName;

所以在声明变量的文件中尝试这个：

extern QList<QRadioButton *> colorList;