Question

我对我的代码进行了一些编辑，然后做了大约15＆＃34;撤消＆＃34;回到我上次编译成功的地方的操作，只是代替编译而得到了这个从未见过的错误：

expected unqualified-id before 'nullptr'

双击错误会将我带到qcompilerdetection.h的以下部分，这是我从未知道的文件。我对代码的编辑怎么可能搞乱这个文件？或者这是真正问题的误导？我知道我已经出现错误，因为代码中的某个地方缺少一个支架...所以我检查了我在上次成功编译和这个编辑之间编辑的每一行代码。不幸的是，我是一个白痴并在关闭程序之前，重做所有内容以确定是否修复了它。所以现在我不知道要修改什么，而且如果不进一步破坏我的代码，我就会做太多的菜鸟做任何事情。

/*
 * C++11 keywords and expressions
 */
#ifdef Q_COMPILER_NULLPTR
# define Q_NULLPTR         nullptr
#else
# define Q_NULLPTR         NULL
#endif

#ifdef Q_COMPILER_DEFAULT_MEMBERS
#  define Q_DECL_EQ_DEFAULT = default
#else
#  define Q_DECL_EQ_DEFAULT
#endif

#ifdef Q_COMPILER_DELETE_MEMBERS
# define Q_DECL_EQ_DELETE = delete
#else
# define Q_DECL_EQ_DELETE
#endif

具体来说：

# define Q_NULLPTR         nullptr
                           ^

如果知道的话，我正在使用Raspberry Pi 3在Qt5中设置QThread。之前从未见过像这样的问题，只有我实际编写的代码中的错误。这是我调试器派上用场的地方吗？我不知道如何在Qt Creator中使用它。

如果它有助于查看......这是我正在处理的代码。

press.cpp

中的

#include <QDebug>
#include <wiringPi.h>
#include "functions.h"
#include "press.h"

#define PUMP 21
#define SOLENOID_DWN 24
#define SOLENOID_UP 25
#define LIGHT_LEFT 26
#define LIGHT_RIGHT 27
#define LASER 28
#define ENCODER_A 0
#define ENCODER_B 2
#define PEDAL_RIGHT 12
#define PEDAL_LEFT 13
#define HOME 14

Press::Press()
{

}

void Press::programRun() {
    qDebug() << "Hunting Position...";
    qDebug() << positionTarget;
    digitalWrite(PUMP,HIGH);
    digitalWrite(SOLENOID_DWN,HIGH);
    upFlag = 0;
    while (pos > positionTarget){
        if (stopFlag == 1){
            emit stop();
            qDebug() << "emit stopped";
            return;
        }
        if (pausedFlag == 1){
            if (digitalRead(PEDAL_LEFT) == LOW){
                //Functions::programUnpause();
                emit resume();
                qDebug() << "emit resumed";
                delay(100);
                while (digitalRead(PEDAL_LEFT) == LOW){}
                delay(100);
            }
        }
        if (digitalRead(PEDAL_RIGHT) == LOW){
            emit stop();
            //Functions::programStop();
            delay(100);
            while (digitalRead(PEDAL_RIGHT) == LOW){}
            delay(100);
        }
        if (digitalRead(PEDAL_LEFT) == LOW){
            //Functions::programPause();
            emit pause();
            delay(100);
            while (digitalRead(PEDAL_LEFT) == LOW){}
            delay(100);
        }
        delayMicroseconds(30);
    }
    //Functions::solenoidOff();
    //Functions::solenoidUp();
    upFlag = 1;
    //Functions::programPause();
    emit pause();
    while (digitalRead(HOME) == HIGH){
        if (stopFlag == 1){
            emit stop();
            qDebug() << "emit stopped";
            return;
        }
        if (pausedFlag == 1){
            if (digitalRead(PEDAL_LEFT) == LOW){
                //Functions::programUnpause();
                emit resume();
                qDebug() << "emit resumed";
                delay(100);
                while (digitalRead(PEDAL_LEFT) == LOW){}
                delay(100);
            }
        }
        if (digitalRead(PEDAL_RIGHT) == LOW){
            emit stop();
            //Functions::programStop();
            delay(100);
            while (digitalRead(PEDAL_RIGHT) == LOW){}
            delay(100);
        }
        if (digitalRead(PEDAL_LEFT) == LOW){
            //Functions::programPause();
            emit pause();
            qDebug() << "emit paused";
            delay(100);
            while (digitalRead(PEDAL_LEFT) == LOW){}
            delay(100);
        }
        delayMicroseconds(30);
    }
    qDebug() << "FINISHED";
    emit stop();
    Functions::solenoidOff();
}

并在main.cpp

#include <QCursor>
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include <QFile>
#include <QByteArray>
#include <QJsonObject>
#include <QJsonDocument>
#include <QJsonArray>
#include <QFuture>
#include <QThread>
#include <QtConcurrent>
#include <QObject>
#include <wiringPi.h>
#include <pthread.h>
#include "datahandler.h"
#include "functions.h"
#include "press.h"

#define PUMP 21
#define SOLENOID_DWN 24
#define SOLENOID_UP 25
#define LIGHT_LEFT 26
#define LIGHT_RIGHT 27
#define LASER 28
#define ENCODER_A 0
#define ENCODER_B 2
#define PEDAL_RIGHT 12
#define PEDAL_LEFT 13
#define HOME 14

QScopedPointer<Functions> myFunctions(new Functions);
QScopedPointer<DataHandler> myData(new DataHandler);

QThread* thread = new QThread;
Press* pressProgram = new Press();

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    app.setOverrideCursor( QCursor( Qt::BlankCursor ) );    //Hide the cursor

    pressProgram->moveToThread(thread);
    QObject::connect(thread, SIGNAL (started()), pressProgram, SLOT (programRun()));
    QObject::connect(pressProgram, SIGNAL (stop()), thread, SLOT (quit()));
    QObject::connect(pressProgram, SIGNAL (stop()), thread, SLOT (deleteLater()));
    QObject::connect(pressProgram, SIGNAL (stop()), pressProgram, SLOT (deleteLater()));
    //thread->start();

    QQmlApplicationEngine engine;
    engine.rootContext()->setContextProperty("pressProgram",pressProgram);
    engine.rootContext()->setContextProperty("myFunctions",myFunctions.data());
    engine.rootContext()->setContextProperty("myData",myData.data());
    engine.rootContext()->setContextProperty("noteProfileArray",noteProfileArray);
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    return app.exec();
}

Answer 1

原来这种情况属于所有情况的99％：语法错误。

在我认为没有编辑的内容中发现了一行错误的代码，并且IDE没有将其挑出来，但需要修复。我怀疑，头文件错误是一个误导，我真的很感激评论：

＆＃34;编译某些.cpp文件时，通常会出现头文件中的错误。＆＃34;

很高兴知道我的代码没有直接破坏编译器级别的文件，而是导致任何数量的奇怪背景事物出错，表现为看似根深蒂固的问题。

旁注：我认为我犯了这个错误是因为我编辑了多个.cpp文件而且必须忘记＆＃34;撤消＆＃34;其中之一。我希望有一种方法可以在Qt Creator项目中全局撤消操作。

C ++ 11 - ＆＃34;在＆null;之前预期的不合格ID＆＃39; nullptr＆＃39; ＆＃34;

1 个答案: