Question

我想从文本文件中读取字符串（数据）并将数据写入QDoubleSpinBox。因此我使用了：

void GUIsubclassKuehniGUI::LoadDirectory()   
    {
        QString loadedDirectory = QFileDialog::getExistingDirectory(this,
                                                    "/home",tr("Create Directory"),
                                                    QFileDialog::DontResolveSymlinks);
        ui.PathDirectory -> setText(loadedDirectory);

        QFileInfo GeoDat1 = loadedDirectory + "/1_geo.m4";  
        QFileInfo GeoDat2 = loadedDirectory + "/2_geo.m4";         
        QString Value;

        if (GeoDat1.exists() == true)
        {
            QFile GEO (loadedDirectory + "/1_geo.m4");   

            if(GEO.open(QIODevice::ReadOnly | QIODevice::Text))    
            {
                QTextStream Stream (&GEO); 
                QString Text;
                do
                {
                    Text = Stream.readLine();

                    QString startWith = "start";
                    QString endWith = "stop" ;                                      
                    int start = Text.indexOf(startWith, 0, Qt::CaseInsensitive); 
                    int end = Text.indexOf(endWith, Qt::CaseInsensitive);        

                    if (start != -1)                                            
                        Value = Text.mid(start + startWith.length(), end - ( start +  startWith.length() ) );

qDebug() << Value << (start + startWith.length()) << (end - (start + startWith.length()));


                    double ValueNumber = Value.toDouble();
                    ValueNumber = ui.ValueQDoubleSpinBox->value();
                }
                while(!Text.isNull());
                GEO.close();
            }
       }
       else if (GeoDat2.exists() == true)
       {
           ...
       }
   }

编译时我没有收到任何错误信息，但是当我使用方法LoadDirectory时，QString“Value”搜索文件“/1_geo.m4”的方法“QString :: indexOf”和“QString :: mid”存在我用QFileInfo :: exists（）证明没有写入QDoubleSpinBox“ValueQDoubleSpinBox”。有人能告诉我它为什么不起作用吗？问候

Answer 1

恕我直言以下几行：

double ValueNumber = Value.toDouble();
ValueNumber = ui.ValueQDoubleSpinBox->value(); // get value from spinbox

必须更改为：

double ValueNumber = Value.toDouble();
ui.ValueQDoubleSpinBox->setValue(ValueNumber); // set value of spinbox

详细信息：http://qt-project.org/doc/qt-4.8/qdoublespinbox.html#value-prop

读取文本文件的值并将值写入QDoubleSpinBox

1 个答案: