C++/Qt/QList

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Add int to QList

  
#include <QtCore>
#include <QDebug>
int main() {
  QList<int> intlist;
  intlist << 2 << 5 << 2 << 4 << 2;
  int findings = 0;
  QListIterator<int> it(intlist);
  while (it.findNext(2))
    findings++;
  qDebug() << findings; // output: 3
  while (it.findPrevious(2))
    findings--;
  qDebug() << findings; // : 0
  return 0;
}


Append and insert into QList

  
/*
 * 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 <QList>
#include <QString>
#include <QtDebug>
void fillAndPrint()
{
  QList<QString> list;
  list << "foo" << "bar" << "baz";
  QString s;
  foreach( s, list )
    qDebug() << s;
}
void constIterators()
{
  QList<int> list;
  list << 23 << 27 << 52 << 52;
  
  QListIterator<int> javaIter( list );
  while( javaIter.hasNext() )
    qDebug() << javaIter.next();
    
  QList<int>::const_iterator stlIter;
  for( stlIter = list.begin(); stlIter != list.end(); ++stlIter )
    qDebug() << (*stlIter);
}
void mutableIterators()
{
  QList<int> list;
  list << 27 << 33 << 61 << 62;
  
  QMutableListIterator<int> javaIter( list );
  while( javaIter.hasNext() )
  {
    int value = javaIter.next() + 1;
    javaIter.setValue( value );
    qDebug() << value;
  }
  
  QList<int>::Iterator stlIter;
  for( stlIter = list.begin(); stlIter != list.end(); ++stlIter )
  {
    (*stlIter) = (*stlIter)*2;
    qDebug() << (*stlIter);
  }
}
void insertAndPrint()
{
  QList<QString> list;
  list << "first";
  list.append( "second" );
  list.prepend( "third" );
  list.insert( 1, "fourth" );
  list.insert( 4, "fifth" );
  
  QString s;
  foreach( s, list )
    qDebug() << s;
}
void miscExamples()
{
  QList<int> list;
  for( int i=0; i<10; i++ )
    list << i;
    
  int sum = list[5] + list.at(7);
}
int main( void )
{
  qDebug() << "Fill and print";
  fillAndPrint();
  
  qDebug() << "Const iterators";  
  constIterators();
  
  qDebug() << "Mutable iterators";
  mutableIterators();
  qDebug() << "Insert and print";
  insertAndPrint();  
  return 0;
}


Delete all elements in a QList

  
#include <QtGui>
#include <QDebug>
int main(int argc, char * argv[]) {
  QApplication app(argc, argv);
  QList<QWidget* > widgetList;
  for (int i = 1; i < 10; i++)
  {
     widgetList.append(new QWidget);
  }
  qDeleteAll(widgetList.begin(), widgetList.end());
  widgetList.clear();
  widgetList.append(new QWidget);
  return 0;
}


Filling Data Structures

  
#include <QList>
#include <QDebug>
int main()
{
  QList<int> values;
  values << 1 << 4 << 7 << 9;
  qFill(values.begin(), values.end(), 0);
  qDebug() << values; // output: ( 0, 0, 0, 0 )
  return 0;
}


Find next element in a QList with QMutableListIterator

  
#include <QtCore>
#include <QDebug>
int main() {
  QList<int> intlist;
  intlist << 2 << 5 << 2 << 4 << 2;
  QMutableListIterator<int> mit(intlist);
  while (mit.findNext(2))
    mit.remove();
  qDebug() << intlist; // output: (5, 4)
  return 0;
}


Foreach loop with QList

  
/*
 * 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 <QList>
#include <QString>
#include <QtDebug>
void fillAndPrint()
{
  QList<QString> list;
  list << "foo" << "bar" << "baz";
  QString s;
  foreach( s, list )
    qDebug() << s;
}
void constIterators()
{
  QList<int> list;
  list << 23 << 27 << 52 << 52;
  
  QListIterator<int> javaIter( list );
  while( javaIter.hasNext() )
    qDebug() << javaIter.next();
    
  QList<int>::const_iterator stlIter;
  for( stlIter = list.begin(); stlIter != list.end(); ++stlIter )
    qDebug() << (*stlIter);
}
void mutableIterators()
{
  QList<int> list;
  list << 27 << 33 << 61 << 62;
  
  QMutableListIterator<int> javaIter( list );
  while( javaIter.hasNext() )
  {
    int value = javaIter.next() + 1;
    javaIter.setValue( value );
    qDebug() << value;
  }
  
  QList<int>::Iterator stlIter;
  for( stlIter = list.begin(); stlIter != list.end(); ++stlIter )
  {
    (*stlIter) = (*stlIter)*2;
    qDebug() << (*stlIter);
  }
}
void insertAndPrint()
{
  QList<QString> list;
  list << "first";
  list.append( "second" );
  list.prepend( "third" );
  list.insert( 1, "fourth" );
  list.insert( 4, "fifth" );
  
  QString s;
  foreach( s, list )
    qDebug() << s;
}
void miscExamples()
{
  QList<int> list;
  for( int i=0; i<10; i++ )
    list << i;
    
  int sum = list[5] + list.at(7);
}
int main( void )
{
  qDebug() << "Fill and print";
  fillAndPrint();
  
  qDebug() << "Const iterators";  
  constIterators();
  
  qDebug() << "Mutable iterators";
  mutableIterators();
  qDebug() << "Insert and print";
  insertAndPrint();  
  return 0;
}


QList of int

  /*
 * 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 <QList>
#include <QString>
#include <QtDebug>
void fillAndPrint()
{
  QList<QString> list;
  list << "foo" << "bar" << "baz";
  QString s;
  foreach( s, list )
    qDebug() << s;
}
void constIterators()
{
  QList<int> list;
  list << 23 << 27 << 52 << 52;
  
  QListIterator<int> javaIter( list );
  while( javaIter.hasNext() )
    qDebug() << javaIter.next();
    
  QList<int>::const_iterator stlIter;
  for( stlIter = list.begin(); stlIter != list.end(); ++stlIter )
    qDebug() << (*stlIter);
}
void mutableIterators()
{
  QList<int> list;
  list << 27 << 33 << 61 << 62;
  
  QMutableListIterator<int> javaIter( list );
  while( javaIter.hasNext() )
  {
    int value = javaIter.next() + 1;
    javaIter.setValue( value );
    qDebug() << value;
  }
  
  QList<int>::Iterator stlIter;
  for( stlIter = list.begin(); stlIter != list.end(); ++stlIter )
  {
    (*stlIter) = (*stlIter)*2;
    qDebug() << (*stlIter);
  }
}
void insertAndPrint()
{
  QList<QString> list;
  list << "first";
  list.append( "second" );
  list.prepend( "third" );
  list.insert( 1, "fourth" );
  list.insert( 4, "fifth" );
  
  QString s;
  foreach( s, list )
    qDebug() << s;
}
void miscExamples()
{
  QList<int> list;
  for( int i=0; i<10; i++ )
    list << i;
    
  int sum = list[5] + list.at(7);
}
int main( void )
{
  qDebug() << "Fill and print";
  fillAndPrint();
  
  qDebug() << "Const iterators";  
  constIterators();
  
  qDebug() << "Mutable iterators";
  mutableIterators();
  qDebug() << "Insert and print";
  insertAndPrint();  
  return 0;
}


QList of QString

  
/*
 * 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 <QList>
#include <QString>
#include <QtDebug>
void fillAndPrint()
{
  QList<QString> list;
  list << "foo" << "bar" << "baz";
  QString s;
  foreach( s, list )
    qDebug() << s;
}
void constIterators()
{
  QList<int> list;
  list << 23 << 27 << 52 << 52;
  
  QListIterator<int> javaIter( list );
  while( javaIter.hasNext() )
    qDebug() << javaIter.next();
    
  QList<int>::const_iterator stlIter;
  for( stlIter = list.begin(); stlIter != list.end(); ++stlIter )
    qDebug() << (*stlIter);
}
void mutableIterators()
{
  QList<int> list;
  list << 27 << 33 << 61 << 62;
  
  QMutableListIterator<int> javaIter( list );
  while( javaIter.hasNext() )
  {
    int value = javaIter.next() + 1;
    javaIter.setValue( value );
    qDebug() << value;
  }
  
  QList<int>::Iterator stlIter;
  for( stlIter = list.begin(); stlIter != list.end(); ++stlIter )
  {
    (*stlIter) = (*stlIter)*2;
    qDebug() << (*stlIter);
  }
}
void insertAndPrint()
{
  QList<QString> list;
  list << "first";
  list.append( "second" );
  list.prepend( "third" );
  list.insert( 1, "fourth" );
  list.insert( 4, "fifth" );
  
  QString s;
  foreach( s, list )
    qDebug() << s;
}
void miscExamples()
{
  QList<int> list;
  for( int i=0; i<10; i++ )
    list << i;
    
  int sum = list[5] + list.at(7);
}
int main( void )
{
  qDebug() << "Fill and print";
  fillAndPrint();
  
  qDebug() << "Const iterators";  
  constIterators();
  
  qDebug() << "Mutable iterators";
  mutableIterators();
  qDebug() << "Insert and print";
  insertAndPrint();  
  return 0;
}


Quick sort QList

  
#include <QList>
#include <QtAlgorithms>   // for qSort()
#include <QStringList>
#include <QDebug>
class CaseIgnoreString : public QString {
public:
    CaseIgnoreString(const QString& other = QString()) : QString(other) {}
    bool operator<(const QString & other) const {
        return toLower() < other.toLower();
    }
    bool operator==(const QString& other) const {
        return toLower() == other.toLower();
    }
};
int main() {
    CaseIgnoreString s1("A"), s2("b"), s3 ("C"), s4("d"), s5 ("D");
    QList<CaseIgnoreString> namelist;
    namelist << s5 << s1 << s3 << s4 << s2;
 
    qSort(namelist.begin(), namelist.end());
    int i=0;
    foreach (QString stritr, namelist) {
        qDebug() << QString("namelist[%1] = %2").arg(i++).arg(stritr) ;
    }
    QStringList strlist;
    strlist << s5 << s1 << s3 << s4 << s2; 
    qSort(strlist.begin(), strlist.end());
    qDebug() << "StringList sorted: " + strlist.join(", ") << endl;
    return 0;
}


Sorting QList

  
#include <QList>
#include <QDebug>
int main()
{
  QList<int> values;
  values << 1 << 10 << 5 << 6 << 7 << 3;
  qSort(values);
  qDebug() << values; // output: ( 1, 3, 5, 6, 7, 10 )
  return 0;
}