QT 笔记 01

来源：互联网发布：张靓颖冯轲sm 知乎编辑：程序博客网时间：2024/06/05 15:49

<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 用法

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

QMutableListIterator 用法

    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();        else            i.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 用法

    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;

QVarient用法：

    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);    }

Algorithms用法：

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

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