（C ++ QT）QList只允许追加常量类对象？ [英] (C++ QT) QList only allows appending constant class objects?

问题描述

我对QT很新。我一直在搞乱它一个星期。我在尝试向Qlist中添加自定义数据类型时遇到错误。

I'm pretty new to QT. I've been messing with it for a week now. I came across a error while I was trying to add a custom datatype to a Qlist like so

QObject parent;

QList<MyInt*> myintarray;

myintarray.append(new const MyInt(1,"intvar1",&parent));
myintarray.append(new const MyInt(2,"intvar2",&parent));
myintarray.append(new const MyInt(3,"intvar3",&parent));

，我的MyInt类是一个简单的int包装，看起来像这样

and my MyInt class is a simple wrapper for int and looks something like this

#ifndef MYINT_H
#define MYINT_H

#include <QString>
#include <QObject>

class MyInt : public QObject
{ 
 Q_OBJECT

 public:

MyInt(const QString name=0, QObject *parent = 0);
MyInt(const int &value,const QString name=0, QObject *parent = 0);
MyInt(const MyInt &value,const QString name=0,QObject *parent = 0);
int getInt() const;

public slots:
void setInt(const int &value);
void setInt(const MyInt &value);

signals:
 void valueChanged(const int newValue);

private:
int intStore;

};

#endif

我在Qlist追加的错误

the error i'm getting during the Qlist append

错误：无法从'const
MyInt *'转换为'MyInt *'错误：

初始化'void
的参数1'QList :: append（const T&）[with T =
MyInt *]'

error: invalid conversion from 'const MyInt*' to 'MyInt*' error:
initializing argument 1 of 'void QList::append(const T&) [with T = MyInt*]'

如果任何人可以指出我做错了什么，这将是真棒。

If anyone can point out what i'm doing wrong, that would be awesome.

推荐答案

：

QList< MyInt *> myintarray;

然后您稍后尝试附加

myintarray.append(new const MyInt(1,"intvar1",&parent));

问题是新的const MyInt正在创建一个const MyInt *，你不能分配给

The problem is new const MyInt is creating a const MyInt *, which you can't assign to a MyInt * because it loses the constness.

您需要更改QList以容纳const MyInts，如下所示：

You either need to change your QList to hold const MyInts like so :

QList< const MyInt *> myintarray;

或者您不需要通过将附加内容更改为以下内容来创建const MyInt *：

or you need to not create a const MyInt * by changing your appends to:

myintarray.append(new MyInt(1,"intvar1",&parent));

您将选择的方法将取决于您想要如何使用QList。你只想要const MyInt *，如果你永远不想改变MyInt

The method you will choose will depend on exactly how you want to use your QList. You only want const MyInt * if you never want to change the data in your MyInt

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