QT示例代码【积累】

示例一：QRadioButton 

Foundations of Qt Development/Chapter03/radiobutton/main.cpp /* * Copyright (c) 2006-2007, Johan Thelin * * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of APress nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */ #include <QApplication> #include <QGroupBox> #include <QRadioButton> #include <QButtonGroup> #include <QGridLayout> int main( int argc, char **argv ) { QApplication app( argc, argv ); QGroupBox box( "Printing Options" ); QRadioButton *portrait = new QRadioButton( "Portrait" ); QRadioButton *landscape = new QRadioButton( "Landscape" ); QRadioButton *color = new QRadioButton( "Color" ); QRadioButton *bw = new QRadioButton( "B&W" ); QButtonGroup *orientation = new QButtonGroup( &box ); QButtonGroup *colorBw = new QButtonGroup( &box ); orientation->addButton( portrait ); orientation->addButton( landscape ); colorBw->addButton( color ); colorBw->addButton( bw ); QGridLayout *grid = new QGridLayout( &box ); grid->addWidget( portrait, 0, 0 ); grid->addWidget( landscape, 0, 1 ); grid->addWidget( color, 1, 0 ); grid->addWidget( bw, 1, 1 ); box.show(); return app.exec(); } 

判断单选按钮被选定：if( radiobtn->ischecked() ) {...}

实例二：拦截关闭事件

通过实现closeEvent函数，就可以以对关闭窗口消息进行拦截，比如程序还没有完成工作时，可以弹出警告窗口，即使用户确认退出操作

 

在头文件中，需要加入#include <QCloseEvent>：

#ifndef TEST_H #define TEST_H #include <QDialog> #include <QCloseEvent> class ClientTest : public QDialog { Q_OBJECT public: ClientTest(); void closeEvent(QCloseEvent *event); //后边的具体实现省略 ... }; #endif 在cpp文件中，对closeEvent函数进行实现： void ClientTest::closeEvent(QCloseEvent *event) { QMessageBox::StandardButton button; button = QMessageBox::question(this, tr("退出程序"), QString(tr("警告：程序有一个任务正在运行中，是否结束操作退出?")), QMessageBox::Yes | QMessageBox::No); if (button == QMessageBox::No) { event->ignore(); //忽略退出信号，程序继续运行 } else if (button == QMessageBox::Yes) { event->accept(); //接受退出信号，程序退出 } } 

 实例三：QString与int/char的转换

QString转成char*

QString str1 = "Test";
QByteArray ba = str1.toLatin1();
char *c_str2 = ba.data(); 

char * 与 const char *的转换
char *ch1="hello11";
const char *ch2="hello22";
ch2 = ch1;//不报错，但有警告
ch1 = (char *)ch2;

 

char 转换为 QString
其实方法有很多中，我用的是：
char a='b';
QString str;
str=QString(a);

 

QString 转换为 char
方法也用很多中
QString str="abc";
char *ch;
ch = str.toLatin1.data();

 

QByteArray 转换为 char *
char *ch;//不要定义成ch[n];
QByteArray byte;
ch = byte.data();

 

char * 转换为 QByteArray
char *ch;
QByteArray byte;
byte = QByteArray(ch);

 

QString 转换为 QByteArray
QByteArray byte;
QString string;
byte = string.toAscii();

QByteArray 转换为 QString
QByteArray byte;
QString string;
string = QString(byte);
这里再对这俩中类型的输出总结一下：
qDebug()<<"print";
qDebug()<<tr("print");
qDebug()<<ch;(ch 为char类型)
qDebug()<<tr(ch);
qDebug()<<byteArray;(byteArray是QByteArray类型)
qDebug()<<tr(byteArray);
qDebug()<<str;(str 为Qstring类型)
但是qDebug()<<tr(str);是不可以的，要想用tr()函数输出QString类型的字符则要如下：
qDebug()<<tr(str.toLatin1);

 

int 转 QString
int a=10;
QString b;
b=QString::number(a)

 

QString 转int
QString a="120"
int b;
b=a.toInt( )
string --> QString

QString::fromStdString(string)