Редактирование: WxWidgets FAQ Helper classes

Материал из Wiki.crossplatform.ru

Перейти к: навигация, поиск
Внимание: Вы не представились системе. Ваш IP-адрес будет записан в историю изменений этой страницы.
Правка может быть отменена. Пожалуйста, просмотрите сравнение версий, чтобы убедиться, что это именно те изменения, которые вас интересуют, и нажмите «Записать страницу», чтобы изменения вступили в силу.
Текущая версия Ваш текст
Строка 1: Строка 1:
 +
wxWidgets consists of a large group of helper classes, that help programmers to do their job.
 +
These include classes for working with strings, files, xml files, streams, database or network.
 +
Here we will show only a tiny drop of the whole lake.
 +
wxWidgets library can be used to create console and gui applications. In this chapter, we will illustrate some of the  helper classes in console based applications.
 +
 +
== Console ==
 +
This is a simple console application. The application puts some text into the console window.
 +
<source lang="cpp">
 +
#include &lt;wx/string.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
  wxPuts(wxT("A wxWidgets console application"));
 +
}
 +
</source>
 +
 +
<source lang="cpp">
 +
A wxWidgets console application
 +
</source>
 +
 +
== wxString ==
 +
This is probably the most useful class. wxString is a class representing a character string.
 +
 +
In the following example, we define three wxStrings. We create one string of these strings using addition operation.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/string.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
  wxString str1 = wxT("Linux");
 +
  wxString str2 = wxT("Operating");
 +
  wxString str3 = wxT("System");
 +
 +
  wxString str = str1 + wxT(" ") + str2 + wxT(" ") + str3;
 +
 +
  wxPuts(str);
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
Linux Operating System
 +
</source>
 +
 +
The Printf() method is used to format strings.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/string.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
 +
  int flowers = 21;
 +
 +
  wxString str;
 +
  str.Printf(wxT("There are %d red roses."), flowers);
 +
 
 +
  wxPuts(str);
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
There are 21 red roses.
 +
</source>
 +
 +
The following example checks, whether a string contains another string. For this we have a <i>Contains()</i> method.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/string.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
 +
  wxString str = wxT("The history of my life");
 +
 +
  if (str.Contains(wxT("history"))) {
 +
      wxPuts(wxT("Contains!"));
 +
  }
 +
 +
 +
  if (!str.Contains(wxT("plain"))) {
 +
      wxPuts(wxT("Does not contain!"));
 +
  }
 +
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
Contains!
 +
Does not contain!
 +
</source>
 +
 +
The <i>Len()</i> method returns the number of characters in the string.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/string.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
  wxString str = wxT("The history of my life");
 +
  wxPrintf(wxT("The string has %d characters\n"), str.Len());
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
The string has 22 characters
 +
</source>
 +
 +
The <i>MakeLower()</i> and <i>MakeUpper()</i> methods make characters lower case and upper case.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/string.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
  wxString str = wxT("The history of my life");
 +
 +
  wxPuts(str.MakeLower());
 +
  wxPuts(str.MakeUpper());
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
the history of my life
 +
THE HISTORY OF MY LIFE
 +
 +
</source>
 +
 +
== Utility functions ==
 +
wxWidgets has several handy utility functions for executing a process, getting a home user directory or getting the OS name.
 +
 +
In the following example, we execute the ls command. For this, we have the wxShell() function. Unix only.
 +
<source lang="cpp">
 +
#include &lt;wx/string.h&gt;
 +
#include &lt;wx/utils.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
 +
  wxShell(wxT("ls -l"));
 +
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
total 40
 +
-rwxr-xr-x 1 vronskij vronskij  9028 2007-09-06 22:10 basic
 +
-rw-r--r-- 1 vronskij vronskij    95 2007-09-06 22:09 basic.cpp
 +
-rw-r--r-- 1 vronskij vronskij  430 2007-09-06 00:07 basic.cpp~
 +
-rwxr-xr-x 1 vronskij vronskij 11080 2007-09-05 23:17 console
 +
-rw-r--r-- 1 vronskij vronskij  500 2007-09-05 23:17 console.cpp
 +
-rw-r--r-- 1 vronskij vronskij  485 2007-09-05 23:16 console.cpp~
 +
</source>
 +
 +
Next we will we will get the home user directory, os name, user name, host name and total free memory.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/string.h&gt;
 +
#include &lt;wx/utils.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
  wxPuts(wxGetHomeDir());
 +
  wxPuts(wxGetOsDescription());
 +
  wxPuts(wxGetUserName());
 +
  wxPuts(wxGetFullHostName());
 +
 +
  long mem = wxGetFreeMemory().ToLong();
 +
 +
  wxPrintf(wxT("Memory: %ld\n"), mem);
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
/home/vronskij
 +
Linux 2.6.20-16-generic i686
 +
jan bodnar
 +
spartan
 +
Memory: 741244928
 +
</source>
 +
 +
== Time & date ==
 +
 +
In wxWidgets, we have several classes for working with date & time.
 +
 +
The example shows current date or time in various formats.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/datetime.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
  wxDateTime now = wxDateTime::Now();
 +
 +
  wxString date1 = now.Format();
 +
  wxString date2 = now.Format(wxT("%X"));
 +
  wxString date3 = now.Format(wxT("%x"));
 +
 +
  wxPuts(date1);
 +
  wxPuts(date2);
 +
  wxPuts(date3);
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
 +
Fri Sep  7 21:28:38 2007
 +
21:28:38
 +
09/07/07
 +
</source>
 +
 +
Next we will show current time in different cities.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/datetime.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
  wxDateTime now = wxDateTime::Now();
 +
 +
  wxPrintf(wxT("  Tokyo: %s\n"), now.Format(wxT("%a %T"),
 +
      wxDateTime::GMT9).c_str());
 +
  wxPrintf(wxT("  Moscow: %s\n"), now.Format(wxT("%a %T"),
 +
      wxDateTime::MSD).c_str());
 +
  wxPrintf(wxT("Budapest: %s\n"), now.Format(wxT("%a %T"),
 +
      wxDateTime::CEST).c_str());
 +
  wxPrintf(wxT("  London: %s\n"), now.Format(wxT("%a %T"),
 +
      wxDateTime::WEST).c_str());
 +
  wxPrintf(wxT("New York: %s\n"), now.Format(wxT("%a %T"),
 +
      wxDateTime::EDT).c_str());
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
  Tokyo: Sat 05:42:24
 +
  Moscow: Sat 00:42:24
 +
Budapest: Fri 22:42:24
 +
  London: Fri 22:42:24
 +
New York: Fri 16:42:24
 +
 +
</source>
 +
 +
The following example shows, how we can add date spans to our date/time.
 +
We add one month to the current time.
 +
 +
<source lang="cpp">
 +
 +
#include &lt;wx/datetime.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
  wxDateTime now = wxDateTime::Now();
 +
  wxString date1 = now.Format(wxT("%B %d %Y"));
 +
  wxPuts(date1);
 +
 +
  wxDateSpan span(0, 1);
 +
  wxDateTime then = now.Add(span);
 +
 +
  wxString date2 = then.Format(wxT("%B %d %Y"));
 +
  wxPuts(date2);
 +
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
September 07 2007
 +
October 07 2007
 +
 +
</source>
 +
 +
== Files ==
 +
wxWidgets has several classes to facilitate working with files. This is low level access to files, as opposed to working  with streams.
 +
 +
In the following example, we use the <b>wxFile</b> class to create a new file and write data to it.
 +
We also test, whether the file is opened. Note, that when we create a file, it automatically stays as opened.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/file.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
 +
  wxString str = wxT("You make me want to be a better man.\n");
 +
 +
  wxFile file;
 +
  file.Create(wxT("quote"), true);
 +
 +
  if (file.IsOpened())
 +
      wxPuts(wxT("the file is opened"));
 +
 +
  file.Write(str);
 +
  file.Close();
 +
 +
  if (!file.IsOpened())
 +
      wxPuts(wxT("the file is not opened"));
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
$ ls qoute
 +
ls: qoute: No such file or directory
 +
 +
$ ./createfile
 +
the file is opened
 +
the file is not opened
 +
 +
$ cat quote
 +
You make me want to be a better man.
 +
 +
</source>
 +
 +
The <b>wxTextFile</b> is a simple class which allows to work with text files on line by line basis.
 +
It is easier to work with this class than with wxFile class.
 +
 +
In the next example, we will print the number of lines in a file, first and last lines and finally we will  read and show the contents of the file.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/textfile.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
 +
  wxTextFile file(wxT("test.c"));
 +
 +
  file.Open();
 +
 +
  wxPrintf(wxT("Number of lines: %d\n"), file.GetLineCount());
 +
  wxPrintf(wxT("First line: %s\n"), file.GetFirstLine().c_str());
 +
  wxPrintf(wxT("Last line: %s\n"), file.GetLastLine().c_str());
 +
 +
  wxPuts(wxT("-------------------------------------"));
 +
 +
  wxString s;
 +
 +
  for ( s = file.GetFirstLine(); !file.Eof();
 +
      s = file.GetNextLine() )
 +
  {
 +
      wxPuts(s);
 +
  }
 +
 +
  file.Close();
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
Number of lines: 8
 +
First line: #include <glib.h>
 +
Last line: }
 +
-------------------------------------
 +
#include &lt;glib.h&gt;
 +
#include &lt;glib/gstdio.h&gt;
 +
 +
int main() {
 +
 +
g_mkdir("/home/vronskij/test", S_IRWXU);
 +
 +
}
 +
 +
</source>
 +
 +
The <b>wxDir</b> class allows us to enumerate files and directories.
 +
 +
In the following example, we will print all files and directories available in the  current working directory.
 +
 +
<source lang="cpp">
 +
#include &lt;wx/dir.h&gt;
 +
 +
#include &lt;wx/filefn.h&gt;
 +
 +
int main(int argc, char **argv)
 +
{
 +
 +
  wxDir dir(wxGetCwd());
 +
 +
  wxString file;
 +
 +
  bool cont = dir.GetFirst(&file, wxEmptyString,
 +
      wxDIR_FILES | wxDIR_DIRS);
 +
 +
  while (cont) {
 +
      wxPuts(file);
 +
      cont = dir.GetNext(&file);
 +
  }
 +
}
 +
 +
</source>
 +
 +
<source lang="cpp">
 +
$ ./dir
 +
dir
 +
temp
 +
console
 +
basic.cpp
 +
basic
 +
quote
 +
createfile
 +
console.cpp
 +
basic.cpp~
 +
test.c
 +
console.cpp~
 +
</source>
 +
 +
[[Категория:WxWidgets]]

Пожалуйста, обратите внимание, что все ваши добавления могут быть отредактированы или удалены другими участниками. Если вы не хотите, чтобы кто-либо изменял ваши тексты, не помещайте их сюда.
Вы также подтверждаете, что являетесь автором вносимых дополнений, или скопировали их из источника, допускающего свободное распространение и изменение своего содержимого (см. Wiki.crossplatform.ru:Авторское право). НЕ РАЗМЕЩАЙТЕ БЕЗ РАЗРЕШЕНИЯ ОХРАНЯЕМЫЕ АВТОРСКИМ ПРАВОМ МАТЕРИАЛЫ!


Отменить | Справка по редактированию (в новом окне)
Источник — «http://wiki.crossplatform.ru/index.php/WxWidgets_FAQ_Helper_classes»