C++/Qt/QVector

Материал из C\C++ эксперт
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Copying Container Areas

  

#include <QStringList>
#include <QVector>
#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;
}


creates two containers and compares all the elements for equality:

  
#include <QStringList>
#include <QVector>
#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;
}


Store QPoint in QVector

  
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.
 *
 */
#include <QApplication>
#include <QPixmap>
#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;
}


Using QVector

  
#include <QVector>
#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;
}