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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
< html >
< head >
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< title > isset< / title >
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< link rel = "stylesheet" type = "text/css" href = "../../src/self.css" >
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< meta name = "description" content = "Prüft ob eine Variable existiert" >
< meta name = "keywords" content = "SELFPHP, PHP, Variablen-Funktionen, isset" >
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< meta name = "author" content = "Damir Enseleit, mail@selfphp.info" >
< meta name = "DC.Contributer" content = "Matthias Hupp, m.hupp@selfphp3.de" >
< meta name = "DC.Publisher" content = "Damir Enseleit, mail@selfphp.info" >
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< meta name = "DC.Date" content = "2001-08-02T12:18+01:00" >
< meta name = "DC.Identifier" content = "http://www.selfphp3.de/funktionsreferenz/variablen_funktionen/isset.html" >
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< meta name = "DC.Language" content = "de" >
< meta name = "DC.Rights" content = "../../editorial/index.html" >
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< meta name = "SELF.Firstdate" content = "2001-08-02T12:18+01:00" >
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< meta name = "SELF.Version" content = "1" >
< meta name = "SELF.Pagetype" content = "Information" >
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< meta name = "SELF.Path" content = "SELFPHP == ../../index.php // Funktionsreferenz == ../index.php // Variablen-Funktionen == index.html" >
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< / head >
< body bgcolor = "#FFFFFF" text = "#000000" link = "#AA5522" vlink = "#772200" alink = "#000000" >
< table cellpadding = "4" cellspacing = "0" border = "0" width = "100%" >
< tr >
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< td bgcolor = "#FFEEDD" class = "nav" > < a class = "an" name = "top" > < img src = "../../src/refkap.gif" width = "16" height = "13" border = "0" alt = "Teil von" > < / a > < a href = "../../index.html" > < b > SELFPHP< / b > < / a > /< a href = "../../navigation/index.html" > Navigationshilfen< / a > < img src = "../../src/refkap.gif" width = "16" height = "13" border = "0" alt = "Teil von" > < a href = "../index.html" > < b > Funktionsreferenz< / b > < / a > < img src = "../../src/refkap.gif" width = "16" height = "13" border = "0" alt = "Teil von" > < a href = "index.html" > < b > Variablen-Funktionen< / b > < / a > < / td >
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< / tr >
< / table > < table cellpadding = "4" cellspacing = "0" border = "0" width = "100%" >
< tr >
< td bgcolor = "#EEEEEE" class = "doc" width = "110" > < img src = "../../src/logo.gif" width = "106" height = "109" border = "0" alt = "SEL.html" > < / td >
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< td bgcolor = "#EEEEEE" class = "doc" valign = "bottom" width = "100%" > < h2 > isset< / h2 >
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< tr >
< td bgcolor = "#EEEEEE" class = "doc" valign = "top" align = "center" >
< img src = "../../src/dokx.gif" width = "30" height = "20" vspace = "6" border = "0" alt = "Informationsseite" >
< / td >
< td bgcolor = "#FFFFFF" valign = "top" nowrap >
< p >
< img src = "../../src/down.gif" width = "14" height = "10" border = "0" alt = "nach unten" > < a href = "#befehl" > < b > Befehl< / b > < / a > < br >
< img src = "../../src/down.gif" width = "14" height = "10" border = "0" alt = "nach unten" > < a href = "#version" > < b > Version< / b > < / a > < br >
< img src = "../../src/down.gif" width = "14" height = "10" border = "0" alt = "nach unten" > < a href = "#beschreibung" > < b > Beschreibung< / b > < / a > < br >
< img src = "../../src/down.gif" width = "14" height = "10" border = "0" alt = "nach unten" > < a href = "#beispiel" > < b > Beispiel< / b > < / a > < br >
< img src = "../../src/down.gif" width = "14" height = "10" border = "0" alt = "nach unten" > < a href = "#ausgabe" > < b > Ausgabe< / b > < / a > < br >
< / p >
< / td >
< / tr > < tr > < td colspan = 2 bgcolor = "#EEEEEE" class = "doc" > < a href = "#bottom" > < img src = "../../src/down.gif" width = "14" height = "10" border = "0" alt = "nach unten" > < / a >   < / td > < / tr >
< / table >
< h2 class = "Sh2" > < a class = "an" name = "befehl" > Befehl< / a > < / h2 >
< table width = "100%" cellpadding = 10 > < tr >
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< td class = "xmpcode" bgcolor = "#E4EEFF" > int < b > isset< / b > (mixed var)< / td >
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< / tr > < / table >
< p > < / p >
< table bgcolor = "#EEEEEE" class = "doc" width = "100%" > < tr > < td >
< a href = "#top" > < img src = "../../src/up.gif" width = "14" height = "10" border = "0" alt = "nach oben" > < / a > < a href = "#bottom" > < img src = "../../src/down.gif" width = "14" height = "10" border = "0" alt = "nach unten" > < / a >  
< / td > < / tr > < / table >
< h2 class = "Sh2" > < a class = "an" name = "version" > Version< / a > < / h2 >
< table width = "100%" cellpadding = 10 height = "32" >
< tr >
< td class = "xmpcode" bgcolor = "#E4EEFF" height = "20" >
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< p > PHP 3, PHP 4 > = 4.0b1< / p >
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< / td >
< / tr > < / table >
< p > < / p >
< table bgcolor = "#EEEEEE" class = "doc" width = "100%" > < tr > < td >
< a href = "#top" > < img src = "../../src/up.gif" width = "14" height = "10" border = "0" alt = "nach oben" > < / a > < a href = "#bottom" > < img src = "../../src/down.gif" width = "14" height = "10" border = "0" alt = "nach unten" > < / a >  
< / td > < / tr > < / table >
< h2 class = "Sh2" > < a class = "an" name = "beschreibung" > Beschreibung< / a > < / h2 >
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< table width = "100%" cellpadding = 10 height = "230" >
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< tr >
< td class = "xmpcode" bgcolor = "#E4EEFF" height = "57" >
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< p > Die Funktion isset() ü berprü ft, ob eine Variable oder ein Array
existent ist. Diese< br >
Funktion liefert true zurü ck, wenn die Variable oder das Array existent
ist, sonst< br >
false.< br >
Es gibt eine Besonderheit bei Formularen. Wird ein Formular per Image
gesendet< br >
und Sie mö chten dieses ü berprü fen, so mü ssen Sie bei
der Abfrage ein " _x" < br >
anhä ngen (isset($tag_x)), da bei einem Formular-Tag die X- und Y-Koordinaten< br >
der Mausposition mitgegeben werden.< br >
Wird eine Variable oder ein Array mit unset() wieder freigegeben, so ist
sie bzw.< br >
es als nicht existent anzusehen.< / p >
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< p > Siehe auch:< / p >
< ul >
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< li > < a href = "empty.html" > empty()< / a > < / li >
< li > < a href = "unset.html" > unset()< / a > < / li >
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< / ul >
< / td >
< / tr > < / table >
< p > < / p >
< table bgcolor = "#EEEEEE" class = "doc" width = "100%" > < tr > < td >
< a href = "#top" > < img src = "../../src/up.gif" width = "14" height = "10" border = "0" alt = "nach oben" > < / a > < a href = "#bottom" > < img src = "../../src/down.gif" width = "14" height = "10" border = "0" alt = "nach unten" > < / a >  
< / td > < / tr > < / table >
< h2 class = "Sh2" > < a class = "an" name = "beispiel" > Beispiel< / a > < / h2 >
< table width = "100%" cellpadding = 10 height = "66" >
< tr >
< td class = "xmpcode" bgcolor = "#E4EEFF" >
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< pre > < ?PHP< br > $a = 24; < br > if(isset($a)) echo" \$a ist existent." ;< br > if(!isset($b)) echo" \$b ist nicht existent." ; < br > ?> < / pre >
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< / td >
< / tr > < / table >
< p > < / p >
< table bgcolor = "#EEEEEE" class = "doc" width = "100%" > < tr > < td >
< a href = "#top" > < img src = "../../src/up.gif" width = "14" height = "10" border = "0" alt = "nach oben" > < / a > < a href = "#bottom" > < img src = "../../src/down.gif" width = "14" height = "10" border = "0" alt = "nach unten" > < / a >  
< / td > < / tr > < / table >
< h2 class = "Sh2" > < a class = "an" name = "ausgabe" > Ausgabe< / a > < / h2 >
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< table width = "100%" cellpadding = 10 height = "38" >
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< tr >
< td class = "xmpcode" bgcolor = "#E4EEFF" height = "57" >
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< p > $a ist existent.< br >
$b ist nicht existent.< / p >
< / td >
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< / tr > < / table >
< p > < / p >
< table cellpadding = "4" cellspacing = "0" border = "0" width = "100%" >
< tr > < td colspan = 2 bgcolor = "#EEEEEE" class = "doc" >
< a href = "#top" > < img src = "../../src/up.gif" width = "14" height = "10" border = "0" alt = "nach oben" > < / a >
< / td > < / tr >
< tr >
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< td bgcolor = "#EEEEEE" class = "doc" align = "right" width = "110" > weiter:< a href = "settype.html" > < img src = "../../src/next.gif" width = "10" height = "10" border = "0" hspace = "10" alt = "weiter" > < / a > < / td >
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< td bgcolor = "#FFFFFF" > < img src = "../../src/dok.gif" width = "15" height = "10" border = "0" alt = "Seite" >
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< a href = "settype.html" > < b > settype< / b > < / a > < / td >
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< / tr >
< tr >
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< td bgcolor = "#EEEEEE" class = "doc" align = "right" width = "110" > zurü ck:< a href = "is_string.html" > < img src = "../../src/prev.gif" width = "10" height = "10" border = "0" hspace = "10" alt = "zurück" > < / a > < / td >
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< td bgcolor = "#FFFFFF" width = "100%" > < img src = "../../src/dok.gif" width = "15" height = "10" border = "0" alt = "Seite" >
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< a href = "is_string.html" > < b > is_string< / b > < / a > < / td >
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< / tr >
< tr > < td colspan = 2 bgcolor = "#EEEEEE" class = "doc" >   < / td > < / tr >
< / table > < table cellpadding = "4" cellspacing = "0" border = "0" width = "100%" >
< tr >
< td bgcolor = "#FFEEDD" class = "nav" > < a class = "an" name = "bottom" > < img src = "../../src/refkap.gif" width = "16" height = "13" border = "0" alt = "Teil von" > < / a >
< a href = "../../index.html" > < b > SELFPHP< / b > < / a > /< a href = "../../navigation/index.html" > Navigationshilfen< / a > < img src = "../../src/refkap.gif" width = "16" height = "13" border = "0" alt = "Teil von" >
< a href = "../index.html" > < b > Funktionsreferenz< / b > < / a > < img src = "../../src/refkap.gif" width = "16" height = "13" border = "0" alt = "Teil von" >
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< a href = "index.html" > < b > Variablen-Funktionen< / b > < / a > < / td >
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< / tr >
< / table >
< p > < a class = "an" name = "bottom" > © 2001, 2002, 2003< / A > < img src = "../../src/mail.gif" width = "15" height = "10" border = "0" alt = "E-Mail" > < a href = "mailto:mail@selfphp.info" > Damir Enseleit, mail@selfphp.info< / a > < / p >
< / body >
< / html >