嘗試在樹莓派上部署Qt5應用程序時出現奇怪的錯誤

Question

我有一個在Ubuntu 14.04 LTS上完成的項目，但是隨后，我想測試Raspberry Pi是否能夠運行我的這個小程序。 然后，我按照此鏈接上的說明在Pi上本地編譯和構建qt5。

我已經成功安裝了qt5，甚至可以編譯並運行位於qt示例上的“多維數據集”程序。

之后，我編譯並安裝了我的項目所需的qtmultimedia子模塊。

好的，情況看起來不錯。 然后我在Pi上克隆了我的項目，運行qmake，然后運行了make。 直到...我收到此錯誤消息：

In file included from ../mainWindow.h:14:0,
             from ../main.cpp:3:
../core/core.h: In constructor ‘bumbatv::core::Core::Core()’:
../core/core.h:37:36: error: conversion from ‘int’ to ‘QString’ is ambiguous
../core/core.h:37:36: note: candidates are:
/usr/local/qt5/include/QtCore/qstring.h:649:31: note: QString::QString(const char*)
/usr/local/qt5/include/QtCore/qstring.h:214:14: note: QString::QString(const QChar*, int)
Makefile:2564: recipe for target 'main.o' failed
make: *** [main.o] Error 1

事情是...在代碼的這一特定區域，我沒有從int到QString的轉換！

class Core : public QObject
{
Q_OBJECT
private:
    static Core *instance_;
    QHash <int, Channel*> channels_;
    int currentChannelId_;
    QString computerName_;
    QString projectDirectory_; 
    Definitions::kPlayerStatus player_;
    QHash<int, Media*> medias_;
    QString userEmail_;
    QString userPassword_;
    QString userPasswordEncrypted_;
    bool logged_;

    Core(){
        Channel *channel = new Channel; // This is the error line.
        channels_.insert(channel->getId(),channel);
        currentChannelId_ = channel->getId();
        player_ = Definitions::kStopped;
        logged_ = false;
    }

    Core(const Core&);
    Core& operator=(const Core&);
    /* Protect destructor.
     * Deletes all elements allocated in the Document.
     */
    ~Core()
    {
        // Delete channels
        foreach (Channel *c, channels_)
            delete c;
    }
(...)
}

這是Channel構造函數：

        class Channel : public QObject
{
Q_OBJECT
private:

    static int countChannel_; 
    int idChannel_; 
    QString label_; 
    int currentMediaId_; 
    int totalTime_; 
    int order_; 

    QHash<int, Media*> medias_;  


signals:
    (...)

public:
    Channel(int id = -1, int order = -1, int totalTime = -1, QString label = NULL) {
        if(id==-1){
            idChannel_ = countChannel_++;
        }else{
            idChannel_ = id;
            countChannel_ = countChannel_ <= id ? id+1 : countChannel_;
        }

        order_ = order == -1 ? idChannel_ : order;
        totalTime_ = totalTime == -1 ? 0 : totalTime;
        label_ = label == NULL ? QString("Channel %1").arg(idChannel_+1) : label;
    }

    /* Protect destructor.
     * Deletes all elements allocated in the Channel.
     */
    ~Channel()
    {
        // Delete medias
        foreach (Media *m, medias_)
            delete m;
    }
(...)

}

這是make調用的命令：

/usr/bin/g++ -c -pipe -marm -mfpu=vfp -mtune=arm1176jzf-s -march=armv6zk -mabi=aapcs-linux -mfloat-abi=hard -O2 -std=c++0x -Wall -W -D_REENTRANT -fPIE -DQT_NO_SSL -DQT_NO_DEBUG -DQT_MULTIMEDIAWIDGETS_LIB -DQT_MULTIMEDIA_LIB -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_XML_LIB -DQT_CORE_LIB -I../../vodas_desktop -I. -I/usr/local/qt5/include -I/usr/local/qt5/include/QtMultimediaWidgets -I/usr/local/qt5/include/QtMultimedia -I/usr/local/qt5/include/QtWidgets -I/usr/local/qt5/include/QtGui -I/usr/local/qt5/include/QtNetwork -I/usr/local/qt5/include/QtXml -I/usr/local/qt5/include/QtCore -I. -I/opt/vc/include -I/opt/vc/include/interface/vcos/pthreads -I/opt/vc/include/interface/vmcs_host/linux -I/usr/local/qt5/mkspecs/devices/linux-rasp-pi-g++ -o main.o ../main.cpp

所以...有什么想法嗎？ 我不知道怎么了。 我的代碼在ubuntu和Windows上編譯，沒有此錯誤消息。

Answer 1

QString默認參數無效：

QString label = NULL

NULL只是0的宏，因此您實際上是說QString label = 0 。 QString沒有定義從int創建QString的方法，這就是導致錯誤的原因-在大多數平台上，我猜想QString(const char *)構造函數將通過從0到const char *的隱式轉換來調用const char * 。

您的pi似乎很難弄清楚如何隱式轉換0 。 將其更改為QString label = "" ， QString label = QString()或類似的名稱。