C++/Qt/QVector

Copying Container Areas

<source lang="cpp">

1. include <QStringList>
2. include <QVector>
3. include <QDebug>

int main() {

 QStringList list;
 list << "one" << "two" << "three";
 QVector<QString> vect(list.size());
 qCopy(list.begin(), list.end(), vect.begin());
 qDebug() << vect; // output: ( "one", "two", "three" )
 return 0;

}

 </source>

creates two containers and compares all the elements for equality:

<source lang="cpp">

1. include <QStringList>
2. include <QVector>
3. include <QDebug>

int main() {

 QStringList list;
 list << "one" << "two" << "three";
 QVector<QString> vect(3);
 vect[0] = "one";
 vect[1] = "two";
 vect[2] = "three";
 bool ret = qEqual(list.begin(), list.end(), vect.begin());
 qDebug() << ret; // output: true
 return 0;

}

 </source>

Store QPoint in QVector

<source lang="cpp"> Foundations of Qt Development\Chapter07\drawlines\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.
*
*/

1. include <QApplication>
2. include <QPixmap>
3. include <QPainter>

int main( int argc, char **argv ) {

 QApplication app( argc, argv );
 QPixmap pixmap( 200, 100 );
 pixmap.fill( Qt::white );
 QPainter painter( &pixmap );
 painter.setPen( Qt::black );
 
 QVector<QPoint> polyPoints;
 polyPoints << QPoint( 60, 10 ) << QPoint( 80, 90 ) << QPoint( 75, 10 ) << QPoint( 110, 90 );
 QVector<QPoint> linePoints;
 foreach( QPoint point, polyPoints )
   linePoints << point + QPoint( 80, 0 );
 
 painter.drawLine( QPoint( 10, 10 ), QPoint( 30, 90 ) );
 painter.drawPolyline( polyPoints );
 painter.drawLines( linePoints );
 pixmap.save( "drawlines.png" );
 return 0;

}

 </source>

Using QVector

<source lang="cpp">

1. include <QVector>
2. include <QDebug>

int main() {

 const int n = 10;
 QVector<int> vector(n);
 int * data = vector.data();
 for (int i = 0; i < n; ++i)
 data[i] = i;
 for (int i = 0; i < n; ++i) {
   data[i] * = 2;
   qDebug() << vector.at(i);
 }
 QVector<QString> strvector;
 strvector.append("s");
 if (strvector[0] == "s")
   strvector[0] = "868686876";
 qDebug() << strvector;
 return 0;

}

 </source>