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[C/C++] [C++] zapis struktury
Zdaje sobie sprawę z tego że mój problem jest zapewne trywialny ale proszę o pomoc bo naprawde skonczyły mi się pomysly gdzie moge miec błąd: [błąd-podczas zapisu "program wykonuje nieprawidlową operacje"] [???] [całość jest w klasie,kompilator DevC++] Defincje: struct Point2d{ int x,y; }; struct sPoint{ Point2d pos; bool marked; }sPoint points[100]; struct sWall{ int pt[2]; DWORD size; }sWall walls[100];//sciany Funkcja zapisu: bool Save(char *filename) { FILE* plik = fopen(filename,"wb"); if(!plik) return false; fwrite(&num_pts, sizeof(int), 1, plik); fwrite(points, sizeof(sPoint), num_pts, plik); fwrite(&num_walls,sizeof(int), 1, plik); fwrite(walls, sizeof(sWall), num_walls, plik); fclose(plik); return true; } Analogiczna Funkcja odczytu: bool Open(char *filename) { FILE* plik = fopen(filename,"rb"); if(!plik) return false; fread(&num_pts, sizeof(int), 1, plik); fread(points, sizeof(sPoint), num_pts, plik); fread(&num_walls,sizeof(int), 1, plik); fread(walls, sizeof(sWall), num_walls, plik); fclose(plik); return true; } bardzo proszę o pomoc i ewentualną lekturę
Wed,19 Nov 2008 02:28:05 +0100

[Java] Problem z programem (Switch- case)
Witam wszystkich forumowiczow. Mam taki problem z zadaniem. Dopiero ucze sie JAVY i mam do zrobienia pewien program. W sumie wiekszosc juz mam, ale nie wiem jak zrobic jedna rzecz. A mianowicie jak w ponizszym fragmencie kodu zrobic tak, aby wybor case2 realizowal funkcje UstawMiasto(). Chodzi mi o to, aby wybierajac case2 (auto w drodze) byla realizowana metoda wyboru miasta, do ktorego toretycznie jedzie auto. void RuchSamochod() { String m_polozenie; System.out.println("Czy Samochod aktualnie jest:n"); System.out.println("1- zaparkowanyn"); System.out.println("2- w drodzen"); switch(m_polozenie) { case 1: System.out.println("Samochod odpoczywa na parkingu.n"); case 2: void UstamMiasto(); } void UstamMiasto() { InputStreamReader czytacz_strumienia = new InputStreamReader(System.in); BufferedReader czytacz = new BufferedReader(czytacz_strumienia); try { System.out.println("Podaj gdzie jedzie samochod: "); String polozenie = czytacz.readLine(); m_polozenie = polozenie; } catch(IOException e) { System.out.println("Blad podczas odczytu danych"); } } } Po realizacji tej funkcji tworzone sa obiekty, gdzie na ekranie beda podawane ich parametry, a takze info o polozeniu samochodu. Z góry dziękuję. Pozdro
Wed,19 Nov 2008 02:01:45 +0100

[C# i .NET] Przeciążenie operatorów
Witam wszystkich Moglby ktos w latwy i przejrzysty sposob wytlomaczyc na czym polega przeciążanie operatorów. Podac kilka latwych przykladów!!! Z góry
Wed,19 Nov 2008 01:53:27 +0100

[Java] problem z stateChanged
Witam Mam taki problem, w moim programie chciałbym aby przy zmianie zakladki w JTabbedPane zostało wysłane zapytanie SQL do bazy a rezultat pokazany np w jtable znajdującym sie w tej zakladce. W klasie obslugujacej baze jest funkcja: public boolean pokazZajeciaPoDniach(int dzien) { try { PreparedStatement pstmt = con.prepareStatement("SELECT * FROM lista_zajec WHERE dzien = ?"); pstmt.setInt(1, dzien); ResultSet rs = pstmt.executeQuery(); while (rs.next()){ int rok = rs.getInt("rocznik"); int przedmiot = rs.getInt("przedmiot"); int rodz_zajec = rs.getInt("rodz_zajec"); int grupa = rs.getInt("grupa"); int sala = rs.getInt("sala"); String czas_rozp = rs.getString("czas_rozp"); String czas_zak = rs.getString("czas_zak"); int _dzien = rs.getInt("dzien"); System.out.println(rok + " " + przedmiot + " " + rodz_zajec + " " +grupa+ " "+sala+" "+czas_rozp+" "+czas_zak+" "+ _dzien ); } } catch(SQLException e) { System.out.println("Błąd SQL: "+ e.getMessage()); return false; } return true; } Chciałbym ją wywołać z klasy głównej tak aby została wywolana przy zmianie zakladki jtabbedpane: ChangeListener changeListener = new ChangeListener() { public void stateChanged(ChangeEvent changeEvent) { JTabbedPane sourceTabbedPane = (JTabbedPane) changeEvent.getSource(); int index = sourceTabbedPane.getSelectedIndex(); System.out.println("Tab changed to: " + sourceTabbedPane.getSelectedIndex()); int i =sourceTabbedPane.getSelectedIndex(); i++; System.out.println("Index odpowiadający w bazie to " + i); baza.pokazZajeciaPoDniach(i); } }; próba wywyłania metody dla obiektu baza kończy się Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException Dlaczego? Pozdrawiam
Wed,19 Nov 2008 00:37:24 +0100

[C/C++] [C++ Builder] Zacinanie się TMediaPlayer
Tak powiem krótko i na temat :P. Mianowicie robię gierke, w której odtwarzana jest muzyka w komponencie TMediaPlayer. I jest opcja, że muzyka jest odtwarzana losowo. Ale gdy wylosowal następną piosenke jak ją puszcza to jest takie jakby 'zacięcie programu' na chwile. dzieje się to przez funkcje MediaPlayer->Open(); A jeżeli jej nie użyje, to nie odczyta nastepnej piosenki, tylko bedzie powtarzał tą co byla wczytana na początku. I czy jest jakiś sposób, aby te takie zacięcie programu zlikwidowac? bo bardzo przeszkadza w grze... I SZUKALEM JUZ NA GOOGLE.! Prosze o pomoc....
Wed,19 Nov 2008 00:27:57 +0100

Database (dbm-style) Abstraction Layer Functions

Podręcznik PHP
Poprzedni		Następny

XXIV. Database (dbm-style) Abstraction Layer Functions

Wstęp

These functions build the foundation for accessing Berkeley DB style databases.

This is a general abstraction layer for several file-based databases. As such, functionality is limited to a common subset of features supported by modern databases such as Sleepycat Software's DB2. (This is not to be confused with IBM's DB2 software, which is supported through the ODBC functions.)

Wymagania

The behaviour of various aspects depends on the implementation of the underlying database. Functions such as dba_optimize() and dba_sync() will do what they promise for one database and will do nothing for others. You have to download and install supported dba-Handlers.

Tabela 1. List of DBA handlers

Handler	Notes
`dbm`	Dbm is the oldest (original) type of Berkeley DB style databases. You should avoid it, if possible. We do not support the compatibility functions built into DB2 and gdbm, because they are only compatible on the source code level, but cannot handle the original dbm format.
`ndbm`	Ndbm is a newer type and more flexible than dbm. It still has most of the arbitrary limits of dbm (therefore it is deprecated).
`gdbm`	Gdbm is the GNU database manager.
`db2`	DB2 is Sleepycat Software's DB2. It is described as "a programmatic toolkit that provides high-performance built-in database support for both standalone and client/server applications.
`db3`	DB3 is Sleepycat Software's DB3.
`db4`	DB4 is Sleepycat Software's DB4. This is available since PHP 4.3.2.
`cdb`	Cdb is "a fast, reliable, lightweight package for creating and reading constant databases." It is from the author of qmail and can be found at http://cr.yp.to/cdb.html. Since it is constant, we support only reading operations. And since PHP 4.3.0 we support writing (not updating) through the internal cdb library.
`cdb_make`	Since PHP 4.3.0 we support creation (not updating) of cdb files when the bundled cdb library is used.
`flatfile`	This is available since PHP 4.3.0 for compatibility with the deprecated dbm extension only and should be avoided. However you may use this where files were created in this format. That happens when configure could not find any external library.
`inifile`	This is available since PHP 4.3.3 to be able to modify php.ini files from within PHP scripts. When working with ini files you can pass arrays of the form array(0=>group,1=>value_name) or strings of the form "[group]value_name" where group is optional. As the functions dba_firstkey() and dba_nextkey() return string representations of the key there is a new function dba_key_split() available since PHP 5 which allows to convert the string keys into array keys without loosing `FALSE`.
`qdbm`	This is available since PHP 5.0.0. The qdbm library can be loaded from http://qdbm.sourceforge.net.

When invoking the dba_open() or dba_popen() functions, one of the handler names must be supplied as an argument. The actually available list of handlers is displayed by invoking phpinfo() or dba_handlers().

Instalacja

By using the --enable-dba=shared configuration option you can build a dynamic loadable module to enable PHP for basic support of dbm-style databases. You also have to add support for at least one of the following handlers by specifying the --with-XXXX configure switch to your PHP configure line.

Ostrzeżenie

After configuring and compiling PHP you must execute the following test from commandline: php run-tests.php ext/dba. This shows whether your combination of handlers works. Most problematic are dbm and ndbm which conflict with many installations. The reason for this is that on several systems these libraries are part of more than one other library. The configuration test only prevents you from configuring malfaunctioning single handlers but not combinations.

Tabela 2. Supported DBA handlers

Handler	Configure Switch
`dbm`	To enable support for dbm add `--with-dbm[=DIR]`. Notatka: dbm normally is a wrapper which often results in failures. This means you should only use dbm if you are sure it works and if you really need this format.
`ndbm`	To enable support for ndbm add `--with-ndbm[=DIR]`. Notatka: ndbm normally is a wrapper which often results in failures. This means you should only use ndbm if you are sure it works and if you really need this format.
`gdbm`	To enable support for gdbm add `--with-gdbm[=DIR]`.
`db2`	To enable support for db2 add `--with-db2[=DIR]`. Notatka: db2 conflicts with db3 and db4.
`db3`	To enable support for db3 add `--with-db3[=DIR]`. Notatka: db3 conflicts with db2 and db4.
`db4`	To enable support for db4 add `--with-db4[=DIR]`. Notatka: db4 conflicts with db2 and db3. Notatka: This was added in PHP 4.3.2. In earlier versions of PHP you need to use `--with-db3=DIR` with DIR being the path to db4 library. It is not possible to use db versions starting from 4.1 with PHP prior to version 4.3.0. Also, the db libraries with versions 4.1 through 4.1.24 cannot be used in any PHP version.
`cdb`	To enable support for cdb add `--with-cdb[=DIR]`. Notatka: Since PHP 4.3.0 you can omit DIR to use the bundled cdb library that adds the cdb_make handler which allows creation of cdb files and allows to access cdb files on the network using PHP's streams.
`flatfile`	To enable support for flatfile add `--with-flatfile`. Notatka: This was added in PHP 4.3.0 to add compatibility with deprecated dbm extension. Use this handler only when you cannot install one of the libraries required by the other handlers and when you cannot use bundled cdb handler.
`inifile`	To enable support for inifile add `--with-inifile`. Notatka: This was added in PHP 5.0.0 and allows to read and set microsoft style `.ini` files (like the `php.ini` file).
`qdbm`	To enable support for qdbm add `--with-qdbm[=DIR]`. Notatka: qdbm conflicts with dbm and gdbm. Notatka: This was added in PHP 5.0.0. The qdbm library can be loaded from http://qdbm.sourceforge.net.

Notatka: Up to PHP 4.3.0 you are able to add both db2 and db3 handler but only one of them can be used internally. That means that you cannot have both file formats. Starting with PHP 5.0.0 there is a configuration check avoid such misconfigurations.

Konfiguracja uruchomieniowa

To rozszerzenie nie definiuje posiada żadnych dyrektyw konfiguracyjnych w pliku php.ini.

Typy zasobów

The functions dba_open() and dba_popen() return a handle to the specified database file to access which is used by all other dba-function calls.

Stałe predefiniowane

To rozszerzenie nie posiada żadnych stałych.

Przykłady

Przykład 1. DBA example


<?php

$id = dba_open("/tmp/test.db", "n", "db2");

if (!$id) {
    echo "dba_open failed\n";
    exit;
}

dba_replace("key", "This is an example!", $id);

if (dba_exists("key", $id)) {
    echo dba_fetch("key", $id);
    dba_delete("key", $id);
}

dba_close($id);
?>

DBA is binary safe and does not have any arbitrary limits. However, it inherits all limits set by the underlying database implementation.

All file-based databases must provide a way of setting the file mode of a new created database, if that is possible at all. The file mode is commonly passed as the fourth argument to dba_open() or dba_popen().

You can access all entries of a database in a linear way by using the dba_firstkey() and dba_nextkey() functions. You may not change the database while traversing it.

Przykład 2. Traversing a database


<?php

// ...open database...

$key = dba_firstkey($id);

while ($key != false) {
    if (true) {          // remember the key to perform some action later
        $handle_later[] = $key;
    }
    $key = dba_nextkey($id);
}

foreach ($handle_later as $val) {
    dba_delete($val, $id);
}

?>

Spis treści
dba_close -- Close a DBA database
dba_delete -- Delete DBA entry specified by key
dba_exists -- Check whether key exists
dba_fetch -- Fetch data specified by key
dba_firstkey -- Fetch first key
dba_handlers -- List all the handlers available
dba_insert -- Insert entry
dba_key_split -- Splits a key in string representation into array representation
dba_list -- List all open database files
dba_nextkey -- Fetch next key
dba_open -- Open database
dba_optimize -- Optimize database
dba_popen -- Open database persistently
dba_replace -- Replace or insert entry
dba_sync -- Synchronize database

Poprzedni	Spis treści	Następny
dbplus_xunlockrel	Początek rozdziału	dba_close

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