Question

我是QT新手，所以请保持友好。运行项目时，我始终遇到无法解析的外部符号。我不知道在这里还能做什么。我主要在C＃上做项目，所以我只在C＃中应用对象引用或声明。我一直在寻找解决方案的时间很长，但是我没有运气。

它发生在main.cpp的 layer-> AddLayer（）上

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这是我的Main.cpp：

#include <QCoreApplication>
#include <QFile>
#include <QXmlStreamReader>
#include <QDebug>
#include <iostream>
#include <QtGlobal>
#include <stdio.h>
#include <stdlib.h>
#include "layer.h"

QFile* xmlFile;
QXmlStreamReader* xmlReader;
Layer *layer;

int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);

xmlFile = new QFile("D://composition.svg");

if (!xmlFile->open(QIODevice::ReadOnly | QIODevice::Text))
                qDebug() << ("Load XML File Problem");

xmlReader = new QXmlStreamReader(xmlFile);

//QList<Layer> layerList;

//Parse the XML until we reach end of it
while(!xmlReader->atEnd() && !xmlReader->hasError()) {
        // Read next element
        QXmlStreamReader::TokenType token = xmlReader->readNext();
        //If token is just StartDocument - go to next
        if(token == QXmlStreamReader::StartDocument)
                continue;
        //If token is StartElement - read it
        if(token == QXmlStreamReader::StartElement)
        {
            if(xmlReader->name() == "g")
            {
                foreach(const QXmlStreamAttribute &attr, xmlReader->attributes())
                {
                    layer->AddLayer();
                    int x = 0;
                    if (attr.name().toString() == QLatin1String("id")){
                        *layer->layerId = QString(attr.value().toString());
                        x++;
                    }
                }
            }
            if(xmlReader->name() == "polygon")
            {
                foreach(const QXmlStreamAttribute &attr, xmlReader->attributes())
                {
                    if (attr.name().toString() == QLatin1String("points"))
                    {
                        //Space
                        //QRegExp rx("( )");
                        QStringList query = attr.value().toString().split(QRegExp("( )"));
                        //QString* pointList =  new QString[query.length()];
                        for(int i =0; i<query.length(); i++) {
                            qDebug() << query[i].toLatin1();
                            QString x = "Hi";
                        }
                    }
                }
            }
        }
}

return a.exec();

}

我的layer.h

#ifndef LAYER_H
#define LAYER_H

#include <QCoreApplication>
#include <QFile>
#include <QXmlStreamReader>
#include <QDebug>
#include <iostream>
#include <QtGlobal>
#include <stdio.h>
#include <stdlib.h>

class Layer
{
public:
    Layer();
    QString *layerId;
    QList<Layer> *layerList;
    void *AddLayer();
};
class Polygon
{
public:
    Polygon();
    QString style;
    QPointF points[2];
    QString polygonColor;
    QList<Polygon> polygonList;
    void AddPolygon();
};
#endif // LAYER_H

Layer.cpp：

    #include "layer.h"

Layer::Layer()
{

}
Polygon::Polygon()
{

}
void AddLayer()
{
    Layer* layer =  new Layer();
    //layer->layerList.append(*layer);
}

void AddPolygon()
{
    Polygon* polygon = new Polygon();
    polygon->polygonList.append(*polygon);
}

XMLParse.pro：

    QT += core
QT -= gui

CONFIG += c++11

TARGET = XMLParse
CONFIG += console
CONFIG -= app_bundle

TEMPLATE = app

SOURCES += main.cpp \
    layer.cpp

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

HEADERS += \
    layer.h

Answer 1

您需要将AddLayer中的Layer定义为成员函数。添加Layer::

   void Layer::AddLayer()
    {
        Layer* layer =  new Layer();
        //layer->layerList.append(*layer);
    }

使用图层类时的QT无法解析的外部符号

1 个答案: