Qt常用类

向控制台输出文本

第一个例子，我们采用STL的方式：

console.cpp

#include <iostream>

int main()

{

  std::cout << "console application\n";

}

第二个例子我们用QT4编程库

console2.cpp

#include <QTextStream>

int main()

{

   QTextStream out(stdout);

   out << "console application\n";

}

Output

console application

QFile

写一行字符串到文件中

file.cpp

#include <QTextStream>

#include <QFile>

int main()

{

   QFile data("myfile");

   if (data.open(QFile::WriteOnly)) {

     QTextStream out(&data);

     out << "You make me want to be a better man." << endl;

   }

}

Output

$ cat myfile

You make me want to be a better man.

下面的例子我们输出一段文本到控制台

szerelem

S a régi szeretőmér

mit nem cselekednék,

tengerből a vizet

kanállal lemerném.

S a tenger fenekéről

apró gyöngyöt szednék,

s a régi szeretőmnek

gyöngykoszorút kötnék.

szerelem.cpp

#include <QTextStream>

#include <QFile>

int main()

{

  QFile data("szerelem");

  QString line;

  if (data.open(QFile::ReadOnly)) {

    QTextStream in(&data);

    QTextStream out(stdout);

    out.setCodec("UTF-8");

    in.setCodec("UTF-8");

    do {

      line = in.readLine();

      out << line << endl;

    } while (!line.isNull());

  }

}

Output

 S a régi szeretőmér

mit nem cselekednék,

tengerből a vizet

kanállal lemerném.

S a tenger fenekéről

apró gyöngyöt szednék,

s a régi szeretőmnek

gyöngykoszorút kötnék.

QList

Qt容器类之一

mlist.cpp

#include <QTextStream>

#include <QList>

int main()

{

  QTextStream out(stdout);

  QList<QString> list;

  list << "Balzac" << "Tolstoy" << "Guldbrassen"

       << "London" << "Galsworthy" << "Sienkiewicz";

  qSort(list);

  for (int i = 0; i < list.size(); ++i) {

    out << list.at(i) << endl;

  }

}

Output

Balzac

Galsworthy

Guldbrassen

London

Sienkiewicz

Tolstoy

QDir

管理文件目录

home.cpp

#include <QTextStream>

#include <QDir>

int main()

{

  QTextStream out(stdout);

  QString home = QDir::homePath();

  out << home << endl;

}

Output

/home/vronskij

输出应用程序所在路径中扩展名是.c的全部文件名字

filters.cpp

#include <QTextStream>

#include <QDir>

int main()

{

  QTextStream out(stdout);

  QDir dir;

  QStringList filters;

  filters << "*.c" << "*.c~";

  dir.setNameFilters(filters);

  QFileInfoList list = dir.entryInfoList();

  for (int i = 0; i < list.size(); ++i) {

    QFileInfo fileInfo = list.at(i);

    out << QString("%1").arg(fileInfo.fileName());

    out << endl;

  }

}

Output

$ ls -F

anim*  anim.c  anim.c~  filters*

$ ./filters

anim.c

anim.c~

QTime

输出当前时间

mtime.cpp

#include <QTextStream>

#include <QTime>

int main()

{

   QTextStream out(stdout);

   QTime qtime = QTime::currentTime();

   QString stime = qtime.toString(Qt::LocalDate);

   out << stime << endl;

}

Output

$ ./time

10:30:33 PM

QString

字符串连接

concat.cpp

#include <QTextStream>

int main()

{

   QString a = "Disziplin ";

   QString b = "ist ";

   QString c = "Macht.\n";

   QTextStream out(stdout);

   out << a + b + c;

}

Output

$ ./concat

Disziplin ist Macht.

字符串追加

append.cpp

#include <QTextStream>

int main()

{

   QString string = "Whether I shall ";

   string.append("turn out to be the hero of my own life, \n");

   string.append("or whether that station will be held by anybody else, \n");

   string.append("these pages must show.\n");

   QTextStream out(stdout);

   out << string;

}

Output

$ ./append

Whether I shall turn out to be the hero of my own life,

or whether that station will be held by anybody else,

these pages must show.

参数替换

arg.cpp

#include <QTextStream>

int main()

{

   QString string = "What if I gave you %1 red roses?";

   int num = 21;

   QTextStream out(stdout);

   out << string.arg(num) << endl;

}

Output

$ ./str3

What if I gave you 21 red roses?

输出字符串长度

size.cpp

#include <QTextStream>

int main()

{

 QString string = "The history of my life.";

 QTextStream out(stdout);

 out << "The string has " + QString::number(string.size())

    + " characters." << endl;

}

Output

 ./size

The string has 23 characters.

字符串大小写转换

uplow.cpp

#include <QTextStream>

int main()

{

  QString string = "The history of my life.";

  QTextStream out(stdout);

  out << string.toLower() << endl;

  out << string.toUpper() << endl;

}

Output

$ ./uplow

the history of my life.

THE HISTORY OF MY LIFE.

巴特西

Qt学习之路（1）------Qt常用类用法说明

Qt常用类

向控制台输出文本

QFile

QList

QDir

QTime

QString

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