C++ Qt重载数据流运算符<&书信电报；

在阅读了本文之后，我编写了下面的代码来重载我编写的这个头的位移位

#ifndef CIRCLE_H
#define CIRCLE_H

#include <QVector2D>
#include <QDataStream>

class Circle
{
public:
    Circle(const float radius, const QVector2D centerPostion);

    friend QDataStream& operator <<(QDataStream& stream, const Circle& circle);

private:
    float radius;
    QVector2D centerPostion;
};

#endif // CIRCLE_H

#如果是圆#
#定义圆
#包括
#包括
班级圈子
{
公众：
圆（常量浮动半径、常量QVector2D中心位置）；
friend QDataStream&operator多亏了Jaa-c和RobbieE的评论，我得到了它，最后我对这两个流都超载了：

circle.cpp：

#include "circle.h"

Circle::Circle(float radius, QVector2D centerPostion) :
    radius(radius),
    centerPostion(centerPostion) {}

QDebug operator<<(QDebug stream, const Circle &circle) {
    stream << "Circle[radius = "
           << circle.radius
           << ", centerPosition =  ["
           << circle.centerPostion.x()
           << ", "
           << circle.centerPostion.y()
           << "]]";
    return stream;
}

#包括“circle.h”
圆：：圆（浮动半径，QVector2D中心位置）：
半径（半径），
中心位置（中心位置）{}
QDebug运算符根据，函数签名应该不同。这会产生相同的错误，并且它不允许我写入其他流，例如qInfo（）.
QDebug
与
QDataStream
@RobbieE不一样。这没有多大帮助，我应该使用
QDebug
而不是
QDataStream
？还是我做错了什么？如果你想同时使用
QDebug
和
QDataStream
，你也需要重载
QDebug
的流操作符，它们是不兼容的独立类。好了@Jaa-c，我道歉！
#include "Circle.h"
#include <QDebug>

int main(int argc, char *argv[])
{
    Circle circle = Circle(2, QVector2D(3, 5));
    qDebug() << circle;
}

19:27:38: Running steps for project untitled...
19:27:38: Configuration unchanged, skipping qmake step.
19:27:38: Starting: "/usr/bin/make" 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -c -pipe -g -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk -mmacosx-version-min=10.7 -Wall -W -fPIC -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I../untitled -I. -I../../Qt/5.5/clang_64/lib/QtWidgets.framework/Headers -I../../Qt/5.5/clang_64/lib/QtGui.framework/Headers -I../../Qt/5.5/clang_64/lib/QtCore.framework/Headers -I. -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/System/Library/Frameworks/OpenGL.framework/Headers -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/System/Library/Frameworks/AGL.framework/Headers -I. -I../../Qt/5.5/clang_64/mkspecs/macx-clang -F/Users/laura/Qt/5.5/clang_64/lib -o main.o ../untitled/main.cpp
../untitled/main.cpp:10:14: error: invalid operands to binary expression ('QDebug' and 'Circle')
    qDebug() << circle;
    ~~~~~~~~ ^  ~~~~~~
../../Qt/5.5/clang_64/lib/QtCore.framework/Headers/qdebug.h:129:20: note: candidate function not viable: no known conversion from 'Circle' to 'const void *' for 1st argument; take the address of the argument with &
    inline QDebug &operator<<(const void * t) { stream->ts << t; return maybeSpace(); }
...

#include "circle.h"

Circle::Circle(float radius, QVector2D centerPostion) :
    radius(radius),
    centerPostion(centerPostion) {}

QDebug operator<<(QDebug dbg, const Circle &c) {
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "Hoi!";
    return dbg;
}

#ifndef CIRCLE_H
#define CIRCLE_H

#include <QVector2D>
#include <QD>


class Circle
{
public:
    Circle(const float radius, const QVector2D centerPostion);

    friend QDebug operator<<(QDebug dbg, const Coordinate &c);

private:
    float radius;
    QVector2D centerPostion;
};

#endif // CIRCLE_H

#include "circle.h"

Circle::Circle(float radius, QVector2D centerPostion) :
    radius(radius),
    centerPostion(centerPostion) {}

QDebug operator<<(QDebug stream, const Circle &circle) {
    stream << "Circle[radius = "
           << circle.radius
           << ", centerPosition =  ["
           << circle.centerPostion.x()
           << ", "
           << circle.centerPostion.y()
           << "]]";
    return stream;
}

#ifndef CIRCLE_H
#define CIRCLE_H

#include <QVector2D>
#include <QDebug>
#include <QDataStream>


class Circle
{
public:
    Circle(const float radius, const QVector2D centerPostion);

    friend QDebug operator<<(QDebug stream, const Circle &circle);

private:
    float radius;
    QVector2D centerPostion;
};

#endif // CIRCLE_H