QT 笔记 01

<img src="http://img.blog.csdn.net/20150816095001612?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />

Dialog::Dialog(QWidget *parent): QDialog(parent){label1=new QLabel(this);label1->setText(tr("请输入圆的半径："));lineEdit=new QLineEdit(this);label2=new QLabel(this);button=new QPushButton(this);button->setText(tr("显示对应圆的面积"));QGridLayout *mainLayout=new QGridLayout(this);mainLayout->addWidget(label1,0,0);mainLayout->addWidget(lineEdit,0,1);mainLayout->addWidget(label2,1,0);mainLayout->addWidget(button,1,1);//connect(button,SIGNAL(clicked()),this,SLOT(showArea()));//connect(lineEdit,SIGNAL(textChanged(QString)),this,SLOT(showArea()));}void Dialog::showArea(){bool ok;QString tempStr;QString valueStr=lineEdit->text();int valueInt=valueStr.toInt(&ok);double area=valueInt*valueInt*PI;label2->setText(tempStr.setNum(area));}

    QList<int> list;list<<1<<2<<3<<4<<5;QListIterator<int> i(list);for(;i.hasNext();)qDebug()<<i.next();

    QList<int> list;QMutableListIterator<int> i(list);for(int j=0;j<10;++j)i.insert(j);for(i.toFront();i.hasNext();)qDebug()<<i.next();for(i.toBack();i.hasPrevious();){if(i.previous()%2==0)i.remove();elsei.setValue(i.peekNext()*10);}for(i.toFront();i.hasNext();)qDebug()<<i.next();return 0;}

    QList<int> list;for(int j=0;j<10;j++)list.insert(list.end(),j);QList<int>::iterator i;for(i=list.begin();i!=list.end();++i){qDebug()<<(*i);*i=(*i)*10;}QList<int>::const_iterator ci;for(ci=list.constBegin();ci!=list.constEnd();++ci)qDebug()<<*ci;return 0;

    QMap<QString,QString> map;map.insert("beijing","111");map.insert("shanghai","021");map.insert("nanjing","025");QMapIterator<QString,QString> i(map);for(;i.hasNext();)qDebug()<<"  "<<i.key()<<"  "<<i.next().value();QMutableMapIterator<QString,QString> mi(map);if(mi.findNext("111"))mi.setValue("010");QMapIterator<QString,QString> modi(map);qDebug()<<"  ";for(;modi.hasNext();)qDebug()<<" "<<modi.key()<<"  "<<modi.next().value();return 0;

    QVariant v(709);qDebug()<<v.toInt();QVariant w("How are you! ");qDebug()<<w.toString();QMap<QString,QVariant>map;map["int"]=709;map["double"]=709.709;map["string"]="How are you! ";map["color"]=QColor(255,0,0);qDebug()<<map["int"]<< map["int"].toInt();qDebug()<<map["double"]<< map["double"].toDouble();qDebug()<<map["string"]<< map["string"].toString();qDebug()<<map["color"]<< map["color"].value<QColor>();QStringList sl;sl<<"A"<<"B"<<"C"<<"D";QVariant slv(sl);if(slv.type()==QVariant::StringList){QStringList list=slv.toStringList();for(int i=0;i<list.size();++i)qDebug()<<list.at(i);}

    double a=-19.3,b=9.7;double c=qAbs(a);        //c=19.3double max=qMax(b,c);    //max=c=19.3int bn=qRound(b);        //bn=10int cn=qRound(c);        //cn=19qDebug()<<"a="<<a;qDebug()<<"b="<<b;qDebug()<<"c=qAbs(a)= "<<c;qDebug()<<"qMax(b,c)= "<<max;qDebug()<<"bn=qRound(b)= "<<bn;qDebug()<<"cn=qRound(c)= "<<cn;qSwap(bn,cn);qDebug()<<"qSwap(bn,cn)："<<"bn="<<bn<<" cn="<<cn;return 0;