<?xml version="1.0" encoding="iso-8859-2"?>
 <reference id="ref.funchand">
  <title>Funkce pro prci s funkcemi</title>
  <titleabbrev>Funkce</titleabbrev>

  <partintro>
   <para>
    Vechny tyto funkce pokrvaj rzn aspekty prce s funkcemi.
   </para>
  </partintro>

  <refentry id="function.call-user-func">
   <refnamediv>
    <refname>call_user_func</refname>
    <refpurpose>Zavolat uivatelskou funkci urenou prvnm argumentem</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Popis</title>
     <methodsynopsis>
      <type>mixed</type><methodname>call_user_func</methodname>
      <methodparam><type>string</type><parameter>function_name</parameter></methodparam>
      <methodparam choice="opt"><type>mixed</type><parameter>parameter</parameter></methodparam>
      <methodparam choice="opt"><type>mixed</type><parameter>...</parameter></methodparam>
     </methodsynopsis>
    <para>
     Zavol uivatelsky definouvanou funkci urenou argumentem
     <parameter>function_name</parameter>. Zvate nsledujc ukzku:
     <informalexample>
      <programlisting role="php">
function barber ($type) {
    print "You wanted a $type haircut, no problem";
}
call_user_func ('barber', "mushroom");
call_user_func ('barber', "shave");
      </programlisting>
     </informalexample>
    </para>
   </refsect1>
  </refentry>

  <refentry id="function.create-function">
   <refnamediv>
    <refname>create_function</refname>
    <refpurpose>Vytvoit anonymn (lambda-style) funkci</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Popis</title>
     <methodsynopsis>
      <type>string</type><methodname>create_function</methodname>
      <methodparam><type>string</type><parameter>args</parameter></methodparam>
      <methodparam><type>string</type><parameter>code</parameter></methodparam>
     </methodsynopsis>
    <para>
     Z pedanch argument vytvo anonymn funkci, a vrt uniktn nzev tto
     funkce. <parameter>args</parameter> se obvykle pedv jako string v
     jednoduchch uvozovkch, a doporuujeme to i pro <parameter>code</parameter>.
     Dvodem pro jednoduch uvozovky je ochrana nzv promnnch ped parsovnm,
     pokud pouijete dvojit uvozovky, budete muset oescapovat nzvy promnnch,
     nap. <literal>\$avar</literal>.
    </para>
    <para>
     Tuto funkci mete (napklad) pout k vytvoen funkce z dat shromdnch
     za bhu programu:
     <example>
      <title>
       Vytvoen anonymn funkce pomoc <function>create_function</function>
      </title>
      <programlisting role="php">
$newfunc = create_function('$a,$b','return "ln($a) + ln($b) = ".log($a * $b);');
echo "New anonymous function: $newfunc\n";
echo $newfunc(2,M_E)."\n";
// vstup
// New anonymous function: lambda_1
// ln(2) + ln(2.718281828459) = 1.6931471805599
      </programlisting>
     </example>
     Nebo teba k vytvoen obecnho handleru, kter na pedan argumenty
     aplikuje sadu operac:
     <example>
      <title>
       Vytvoen obecn zpracujc funkce pomoc
       <function>create_function</function>
      </title>
      <programlisting role="php">
function process($var1, $var2, $farr) {
    for ($f=0; $f &lt; count($farr); $f++)
    echo $farr[$f]($var1,$var2)."\n";
}

// create a bunch of math functions
$f1 = 'if ($a &gt;=0) {return "b*a^2 = ".$b*sqrt($a);} else {return false;}';
$f2 = "return \"min(b^2+a, a^2,b) = \".min(\$a*\$a+\$b,\$b*\$b+\$a);";
$f3 = 'if ($a &gt; 0 &amp;&amp; $b != 0) {return "ln(a)/b = ".log($a)/$b;} else {return false;}';
$farr = array(
    create_function('$x,$y', 'return "some trig: ".(sin($x) + $x*cos($y));'),
    create_function('$x,$y', 'return "a hypotenuse: ".sqrt($x*$x + $y*$y);'),
    create_function('$a,$b', $f1),
    create_function('$a,$b', $f2),
    create_function('$a,$b', $f3)
    );

echo "\nUsing the first array of anonymous functions\n";
echo "parameters: 2.3445, M_PI\n";
process(2.3445, M_PI, $farr);

// now make a bunch of string processing functions
$garr = array(
    create_function('$b,$a','if (strncmp($a,$b,3) == 0) return "** \"$a\" '.
    'and \"$b\"\n** Look the same to me! (looking at the first 3 chars)";'),
    create_function('$a,$b','; return "CRCs: ".crc32($a)." , ".crc32(b);'),
    create_function('$a,$b','; return "similar(a,b) = ".similar_text($a,$b,&amp;$p)."($p%)";')
    );
echo "\nUsing the second array of anonymous functions\n";
process("Twas brilling and the slithy toves", "Twas the night", $garr);
      </programlisting>
     </example>
     kdy spustte veuveden kd, vstup bude:
     <informalexample>
      <programlisting>
Using the first array of anonymous functions
parameters: 2.3445, M_PI
some trig: -1.6291725057799
a hypotenuse: 3.9199852871011
b*a^2 = 4.8103313314525
min(b^2+a, a^2,b) = 8.6382729035898
ln(a/b) = 0.27122299212594

Using the second array of anonymous functions
** "Twas the night" and "Twas brilling and the slithy toves"
** Look the same to me! (looking at the first 3 chars)
CRCs: -725381282 , 1908338681
similar(a,b) = 11(45.833333333333%)
      </programlisting>
     </informalexample>
    Ale zejm nejbnjm vyuitm lambda-style (anonymnch) funkc je tvorba
    callback funkc, nap. pro pouit v <function>array_walk</function> nebo
    <function>usort</function>
    <example>
     <title>Vyuit anonymnch funkc jako callback funkc</title>
     <programlisting role="php">
$av = array("the ","a ","that ","this ");
array_walk($av, create_function('&amp;$v,$k','$v = $v."mango";'));
print_r($av);  // for PHP 3 use var_dump()
// outputs:
// Array
// (
//   [0] =&gt; the mango
//   [1] =&gt; a mango
//   [2] =&gt; that mango
//   [3] =&gt; this mango
// )

// an array of strings ordered from shorter to longer
$sv = array("small","larger","a big string","it is a string thing");
print_r($sv);
// outputs:
// Array
// (
//   [0] =&gt; small
//   [1] =&gt; larger
//   [2] =&gt; a big string
//   [3] =&gt; it is a string thing
// )

// sort it from longer to shorter
usort($sv, create_function('$a,$b','return strlen($b) - strlen($a);'));
print_r($sv);
// outputs:
// Array
// (
//   [0] =&gt; it is a string thing
//   [1] =&gt; a big string
//   [2] =&gt; larger
//   [3] =&gt; small
// )
     </programlisting>
    </example>
    </para>
   </refsect1>
  </refentry>

  <refentry id="function.func-get-arg">
   <refnamediv>
    <refname>func_get_arg</refname>
    <refpurpose>Vrtit poloku ze seznamu argument</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Popis</title>
     <methodsynopsis>
      <type>mixed</type><methodname>func_get_arg</methodname>
      <methodparam><type>int</type><parameter>arg_num</parameter></methodparam>
     </methodsynopsis>
    <simpara>
     Vrac argument, kter je na
     <parameter>arg_num</parameter>-t pozici v seznamu argument uiavtelsky
     definovan funkce. Argumenty funkc se potaj od nuly.
     <function>func_get_arg</function> pi voln mimo definici funkce generuje
     varovn.
    </simpara>
    <simpara>
     Pokud je <parameter>arg_num</parameter> vt ne poet skuten pedanch
     argument, vygeneruje varovn a vrt &false;.
    </simpara>
    <para>
     <informalexample>
      <programlisting role="php">
&lt;?php
function foo() {
     $numargs = func_num_args();
     echo "Number of arguments: $numargs&lt;br&gt;\n";
     if ($numargs &gt;= 2) {
     echo "Second argument is: " . func_get_arg (1) . "&lt;br&gt;\n";
     }
}

foo (1, 2, 3);
?&gt;
      </programlisting>
     </informalexample>
    </para>
    <simpara>
     <function>func_get_arg</function> se d pout ve spojen s
     <function>func_num_args</function> a
     <function>func_get_args</function> k tvorb uivatelsky definovanch
     funkc, kter pijmaj promnn poet argument.
    </simpara>
    <note>
     <simpara>
      Tato funkce byla pidna v PHP 4.
     </simpara>
    </note>
   </refsect1>
  </refentry>

  <refentry id="function.func-get-args">
   <refnamediv>
    <refname>func_get_args</refname>
    <refpurpose>Vrtit pole obsahujc seznam argument funkce</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Popis</title>
     <methodsynopsis>
      <type>array</type><methodname>func_get_args</methodname>
      <methodparam><type>void</type><parameter/></methodparam>
     </methodsynopsis>
    <simpara>
     Vrac pole, jeho kad prvek je odpovdajc polokou seznamu argument
     souasn uivatelsky definovan funkce. <function>func_get_args</function>
     pi voln mimo definici funkce generuje varovn.
    </simpara>
    <para>
     <informalexample>
      <programlisting role="php">
&lt;?php
function foo() {
    $numargs = func_num_args();
    echo "Number of arguments: $numargs&lt;br&gt;\n";
    if ($numargs &gt;= 2) {
    echo "Second argument is: " . func_get_arg (1) . "&lt;br&gt;\n";
    }
    $arg_list = func_get_args();
    for ($i = 0; $i &lt; $numargs; $i++) {
    echo "Argument $i is: " . $arg_list[$i] . "&lt;br&gt;\n";
    }
}

foo (1, 2, 3);
?&gt;
      </programlisting>
     </informalexample>
    </para>
    <simpara>
     <function>func_get_args</function> se d pout ve spojen s
     <function>func_num_args</function> a <function>func_get_arg</function> k
     tvorb uivatelsky definovanch funkc, kter pijmaj promnny poet
     argument.
    </simpara>
    <note>
     <simpara>
      Tato funkce byla pidna v PHP 4.
     </simpara>
    </note>
   </refsect1>
  </refentry>

  <refentry id="function.func-num-args">
   <refnamediv>
    <refname>func_num_args</refname>
    <refpurpose>Vrtit poet argument pedanch funkci</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Popis</title>
     <methodsynopsis>
      <type>int</type><methodname>func_num_args</methodname>
      <methodparam><type>void</type><parameter/></methodparam>
     </methodsynopsis>
    <simpara>
     Vrac poet argument pedanch souasn uivatelsky definovan funkci.
     <function>func_num_args</function> pri voln mimo definici funkce generuje
     warning.
     definition.
    </simpara>
    <para>
     <informalexample>
      <programlisting role="php">
&lt;?php
function foo() {
    $numargs = func_num_args();
    echo "Number of arguments: $numargs\n";
}

foo (1, 2, 3);    // Prints 'Number of arguments: 3'
?&gt;
      </programlisting>
     </informalexample>
    </para>
    <simpara>
     <function>func_num_args</function> se d pouit ve spojen s
     <function>func_get_arg</function> a <function>func_get_args</function> k
     tvorb uivatelsky definovanch funkc, kter pijmaj promnn poet
     argument.
    </simpara>
    <note>
     <simpara>
      Tato funkce byla pidna v PHP 4.
     </simpara>
    </note>
   </refsect1>
  </refentry>

  <refentry id="function.function-exists">
   <refnamediv>
    <refname>function_exists</refname>
    <refpurpose>Vrtit &true;, pokud je dan funkce definovna</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Popis</title>
     <methodsynopsis>
      <type>bool</type><methodname>function_exists</methodname>
      <methodparam><type>string</type><parameter>function_name</parameter></methodparam>
     </methodsynopsis>
    <para>
     Ov ptomnost funkce <parameter>function_name</parameter> v seznamu
     definovanch funkc. Pokud dan funkce existuje, vrac &true;,
     jinak &false;.
     <informalexample>
      <programlisting role="php">
if (function_exists('imap_open')) {
    echo "IMAP functions are available.&lt;br&gt;\n";
} else {
    echo "IMAP functions are not available.&lt;br&gt;\n";
}
      </programlisting>
     </informalexample>
     Pozn.: nzev funkce me existovat i v ppad, e je samotn funkce
     nepouiteln kvli konfiguraci nebo volbm zadanm pi kompilaci.
    </para>
    <para>
     Viz tak <function>method_exists</function>.
    </para>
   </refsect1>
  </refentry>

  <refentry id="function.register-shutdown-function">
   <refnamediv>
    <refname>register_shutdown_function</refname>
    <refpurpose>Zaregistrovat funkci pro proveden pi ukonen bhu</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Popis</title>
     <methodsynopsis>
      <type>int</type><methodname>register_shutdown_function</methodname>
      <methodparam><type>string</type><parameter>func</parameter></methodparam>
     </methodsynopsis>
    <simpara>
     Zaregistruje funkci udanou v <parameter>func</parameter> pro proveden
     po dokonen bhu skriptu.
    </simpara>
    <para>
     Bn problmy:
    </para>
    <simpara>
     Jeliko tato funkce neme poslat browseru dn vstup, nebudete ji moci
     debugovat pomoc pkaz jako <function>print</function> nebo
     <function>echo</function>.
    </simpara>
   </refsect1>
  </refentry>

 </reference>

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