Sophie: php-manual-en-4.3.0-2mdk noarch

php-manual-en-4.3.0-2mdk.noarch.rpm

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>Types</TITLE
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><DIV
CLASS="chapter"
><H1
><A
NAME="language.types"
>Chapter 7. Types</A
></H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="language.types.html#language.types.intro"
>Introduction</A
></DT
><DT
><A
HREF="language.types.boolean.html"
>Booleans</A
></DT
><DT
><A
HREF="language.types.integer.html"
>Integers</A
></DT
><DT
><A
HREF="language.types.float.html"
>Floating point numbers</A
></DT
><DT
><A
HREF="language.types.string.html"
>Strings</A
></DT
><DT
><A
HREF="language.types.array.html"
>Arrays</A
></DT
><DT
><A
HREF="language.types.object.html"
>Objects</A
></DT
><DT
><A
HREF="language.types.resource.html"
>Resource</A
></DT
><DT
><A
HREF="language.types.null.html"
>NULL</A
></DT
><DT
><A
HREF="language.pseudo-types.html"
>Pseudo-types used in this documentation</A
></DT
><DT
><A
HREF="language.types.type-juggling.html"
>Type Juggling</A
></DT
></DL
></DIV
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="language.types.intro"
></A
>Introduction</H1
><P
>&#13;   PHP supports eight primitive types.
  </P
><P
>&#13;   Four scalar types:

   <P
></P
><UL
><LI
><P
>&#13;      <A
HREF="language.types.boolean.html"
>boolean</A
>
     </P
></LI
><LI
><P
>&#13;      <A
HREF="language.types.integer.html"
>integer</A
>
     </P
></LI
><LI
><P
>&#13;      <A
HREF="language.types.float.html"
>floating-point number (float)</A
>
     </P
></LI
><LI
><P
>&#13;      <A
HREF="language.types.string.html"
>string</A
>
     </P
></LI
></UL
>

   Two compound types:

   <P
></P
><UL
><LI
><P
>&#13;      <A
HREF="language.types.array.html"
>array</A
>
     </P
></LI
><LI
><P
>&#13;      <A
HREF="language.types.object.html"
>object</A
>
     </P
></LI
></UL
>

   And finally two special types:

   <P
></P
><UL
><LI
><P
>&#13;      <A
HREF="language.types.resource.html"
>resource</A
>
     </P
></LI
><LI
><P
>&#13;      <A
HREF="language.types.null.html"
>NULL</A
>
     </P
></LI
></UL
>

   This manual also introduces some 
   <A
HREF="language.pseudo-types.html"
>pseudo-types</A
> 
   for readability reasons:

   <P
></P
><UL
><LI
><P
>&#13;      <A
HREF="language.pseudo-types.html#language.types.mixed"
>mixed</A
>
     </P
></LI
><LI
><P
>&#13;      <A
HREF="language.pseudo-types.html#language.types.number"
>number</A
>
     </P
></LI
><LI
><P
>&#13;      <A
HREF="language.pseudo-types.html#language.types.mixed"
>callback</A
>
     </P
></LI
></UL
>
   You may also find some references to the type "double". Consider
   double the same as float, the two names exist only for historic
   reasons. 
  </P
><P
>&#13;   The type of a variable is usually not set by the programmer;
   rather, it is decided at runtime by PHP depending on the context in
   which that variable is used.
  </P
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
    If you want to check out the type and value of a certain <A
HREF="language.expressions.html"
>expression</A
>, use
    <A
HREF="function.var-dump.html"
><B
CLASS="function"
>var_dump()</B
></A
>.
   </P
><P
><B
>Note: </B
>
    If you simply want a human-readable representation of the type for
    debugging, use <A
HREF="function.gettype.html"
><B
CLASS="function"
>gettype()</B
></A
>. To check for a certain type,
    do <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>not</I
></SPAN
> use <A
HREF="function.gettype.html"
><B
CLASS="function"
>gettype()</B
></A
>, but use the
    <TT
CLASS="literal"
>is_<TT
CLASS="replaceable"
><I
>type</I
></TT
></TT
> functions. Some
    examples:
    <DIV
CLASS="informalexample"
><A
NAME="AEN3217"
></A
><P
></P
><TABLE
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><TD
><PRE
CLASS="php"
>&#60;?php
$bool = TRUE;   // a boolean
$str  = "foo";  // a string
$int  = 12;     // an integer

echo gettype($bool); // prints out "boolean"
echo gettype($str);  // prints out "string"

// If this is an integer, increment it by four
if (is_int($int)) {
    $int += 4;
}

// If $bool is a string, print it out
// (does not print out anything)
if (is_string($bool)) {
    echo "String: $bool";
}
?&#62;</PRE
></TD
></TR
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><P
></P
></DIV
>
   </P
></BLOCKQUOTE
></DIV
><P
>&#13;   If you would like to force a variable to be converted to a certain
   type, you may either <A
HREF="language.types.type-juggling.html#language.types.typecasting"
>cast</A
> the variable or
   use the <A
HREF="function.settype.html"
><B
CLASS="function"
>settype()</B
></A
> function on it.
  </P
><P
>&#13;   Note that a variable may be evaluated with different values in certain
   situations, depending on what type it is at the time. For more
   information, see the section on <A
HREF="language.types.type-juggling.html"
>Type Juggling</A
>.
  </P
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