Sophie: php-manual-pt_BR-5.2.4-1mdv2008.1 noarch

php-manual-pt_BR-5.2.4-1mdv2008.1.noarch.rpm

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>    (PHP 3 &#62;= 3.0.7, PHP 4, PHP 5)</P
>function_exists&nbsp;--&nbsp;
     Retorna <TT
CLASS="constant"
><B
>TRUE</B
></TT
> se a função dada está definida
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><H2
>Descrição</H2
>bool <B
CLASS="methodname"
>function_exists</B
> ( string function_name )<BR
></BR
><P
>&#13;     Verifica a lista de funções definidas, ambas embutidas (interna) e
     definidas pelo usuário, para <CODE
CLASS="parameter"
>function_name</CODE
>. Retorna <TT
CLASS="constant"
><B
>TRUE</B
></TT
> em caso de sucesso ou <TT
CLASS="constant"
><B
>FALSE</B
></TT
> em falhas.
    </P
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><code><font color="#000000">
<font color="#0000BB">&lt;?php<br /></font><font color="#007700">if (</font><font color="#0000BB">function_exists</font><font color="#007700">(</font><font color="#DD0000">'imap_open'</font><font color="#007700">)) {<br />&nbsp;&nbsp;&nbsp;&nbsp;echo </font><font color="#DD0000">"IMAP functions are available.&lt;br /&gt;\n"</font><font color="#007700">;<br />} else {<br />&nbsp;&nbsp;&nbsp;&nbsp;echo </font><font color="#DD0000">"IMAP functions are not available.&lt;br /&gt;\n"</font><font color="#007700">;<br />}<br /></font><font color="#0000BB">?&gt;</font>
</font>
</code></TD
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>
    </P
><P
>&#13;     Note que o nome da função deve existir se a função chama a si própria
     se torna inútil devido a configuração ou opções de compilação (com a função  
     <A
HREF="ref.image.html"
>image</A
> sendo um exemplo).  
     Note também que <B
CLASS="function"
>function_exists()</B
> irá retornar
     <TT
CLASS="constant"
><B
>FALSE</B
></TT
> para construtores, como <A
HREF="function.include-once.html"
><B
CLASS="function"
>include_once()</B
></A
> 
     e <A
HREF="function.echo.html"
><B
CLASS="function"
>echo()</B
></A
>.
    </P
><P
>&#13;     Veja também <A
HREF="function.method-exists.html"
><B
CLASS="function"
>method_exists()</B
></A
> e 
     <A
HREF="function.get-defined-functions.html"
><B
CLASS="function"
>get_defined_functions()</B
></A
>.
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