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<HTML
><HEAD
><TITLE
>Types</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.41"><LINK
REL="HOME"
TITLE="PHP3 Manual"
HREF="manual.html"><LINK
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TITLE="Syntax and grammar"
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TITLE="Syntax and grammar"
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TITLE="Variables"
HREF="variables.html"></HEAD
><BODY
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>PHP3 Manual</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="lang-syntax.html"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Chapter 5. Syntax and grammar</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="variables.html"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="TYPES"
>Types</A
></H1
><P
>    PHP supports the following types:

    <P
></P
><UL
><LI
><P
><A
HREF="types.html#TYPES.INTEGER"
>integer</A
>
     </P
></LI
><LI
><P
><A
HREF="types.html#TYPES.DOUBLE"
>floating-point numbers</A
>
     </P
></LI
><LI
><P
><A
HREF="types.html#TYPES.STRING"
>string</A
>
     </P
></LI
><LI
><P
><A
HREF="types.html#TYPES.ARRAY"
>array</A
>
     </P
></LI
><LI
><P
><A
HREF="types.html#TYPES.OBJECT"
>object</A
>
    </P
></LI
></UL
>

   </P
><P
>    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
><P
>    If you would like to force a variable to be converted to a certain 
    type, you may either <A
HREF="variables.html#LANG-SYNTAX.TYPECASTING"
>cast</A
> the variable or use 
    the <A
HREF="function.settype.html"
><B
CLASS="FUNCTION"
>settype()</B
></A
> function on it.

   </P
><P
>    Note that a variable may behave in different manners in certain
    situations, depending on what type it is a the time. For more
    information, see the section on <A
HREF="variables.html#VARIABLES.TYPE-JUGGLING"
>Type Juggling</A
>.

   </P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="TYPES.INTEGER"
>Integers</A
></H2
><P
>     Integers can be specified using any of the following syntaxes:
    <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
>$a = 1234; # decimal number
$a = -123; # a negative number
$a = 0123; # octal number (equivalent to 83 decimal)
$a = 0x12; # hexadecimal number (equivalent to 18 decimal)</PRE
><P
></P
></DIV
>

   </P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="TYPES.DOUBLE"
>Floating point numbers</A
></H2
><P
>     Floating point numbers ("doubles") can be specified using any
     of the following syntaxes:
    <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
>$a = 1.234;
$a = 1.2e3;</PRE
><P
></P
></DIV
>

   </P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="TYPES.STRING"
>Strings</A
></H2
><P
>     Strings can be specified using one of two sets of delimiters.
    </P
><P
>     If the string is enclosed in double-quotes ("), variables
     within the string will be expanded (subject to some parsing
     limitations). As in C and Perl, the backslash ("\") character
     can be used in specifying special characters:
    <DIV
CLASS="TABLE"
><P
><B
>Table 5-1. Escaped characters</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><TR
><TH
ALIGN="LEFT"
VALIGN="TOP"
>sequence</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>meaning</TH
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>\n</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>newline</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>\r</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>carriage</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>\t</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>horizontal tab</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>\\</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>backslash</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>\$</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>dollar sign</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="LITERAL"
>\"</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>double-quote</TD
></TR
></TABLE
></DIV
>
    </P
><P
>     You can escape any other character, but a warning will be issued
     at the highest warning level.
    </P
><P
>     The second way to delimit a string uses the single-quote ("'")
     character, which does not do any variable expansion or backslash
     processing (except for "\\" and "\'" so you can insert backslashes
     and single-quotes in a singly-quoted string).

   </P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="TYPES.ARRAY"
>Arrays</A
></H2
><P
>     Arrays actually act like both hash tables (associative arrays)
     and indexed arrays (vectors).

    </P
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="TYPES.ARRAY.SINGLE-DIM"
>Single Dimension Arrays</A
></H3
><P
>      PHP supports both scalar and associative arrays. In fact, there
      is no difference between the two.  You can create an array using
      the <A
HREF="function.list.html"
><B
CLASS="FUNCTION"
>list()</B
></A
> or <A
HREF="function.array.html"
><B
CLASS="FUNCTION"
>array()</B
></A
>
      functions, or you can explicitly set each array element value.

     <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> 
$a[0] = "abc"; 
$a[1] = "def"; 
$b["foo"] = 13;
      </PRE
><P
></P
></DIV
>

     </P
><P
>      You can also create an array by simply adding values to
      the array.

     <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> 
$a[] = "hello"; // $a[2] == "hello"
$a[] = "world"; // $a[3] == "world" 
      </PRE
><P
></P
></DIV
>

     </P
><P
>      Arrays may be sorted using the <A
HREF="function.asort.html"
><B
CLASS="FUNCTION"
>asort()</B
></A
>,
      <A
HREF="function.arsort.html"
><B
CLASS="FUNCTION"
>arsort()</B
></A
>, <A
HREF="function.ksort.html"
><B
CLASS="FUNCTION"
>ksort()</B
></A
>,
      <A
HREF="function.rsort.html"
><B
CLASS="FUNCTION"
>rsort()</B
></A
>, <A
HREF="function.sort.html"
><B
CLASS="FUNCTION"
>sort()</B
></A
>,
      <A
HREF="function.uasort.html"
><B
CLASS="FUNCTION"
>uasort()</B
></A
>, <A
HREF="function.usort.html"
><B
CLASS="FUNCTION"
>usort()</B
></A
>, and
      <A
HREF="function.uksort.html"
><B
CLASS="FUNCTION"
>uksort()</B
></A
> functions depending on the type of
      sort you want.

     </P
><P
>      You can count the number of items in an array using the
      <A
HREF="function.count.html"
><B
CLASS="FUNCTION"
>count()</B
></A
> function.

     </P
><P
>      You can traverse an array using <A
HREF="function.next.html"
><B
CLASS="FUNCTION"
>next()</B
></A
> and
      <A
HREF="function.prev.html"
><B
CLASS="FUNCTION"
>prev()</B
></A
> functions.  Another common way to
      traverse an array is to use the <A
HREF="function.each.html"
><B
CLASS="FUNCTION"
>each()</B
></A
>
      function.

    </P
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="TYPES.ARRAY.MULTI-DIM"
>Multi-Dimensional Arrays</A
></H3
><P
>      Multi-dimensional arrays are actually pretty simple.  For each
      dimension of the array, you add another [key] value to the end:

     <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> 
$a[1]      = $f;               # one dimensional examples
$a["foo"]  = $f;   

$a[1][0]     = $f;             # two dimensional
$a["foo"][2] = $f;             # (you can mix numeric and associative indices)
$a[3]["bar"] = $f;             # (you can mix numeric and associative indices)

$a["foo"][4]["bar"][0] = $f;   # four dimensional!
      </PRE
><P
></P
></DIV
>

     </P
><P
>      You can "fill up" multi-dimensional arrays in many ways,
      but the trickiest one to understand is how to use the
      <A
HREF="function.array.html"
><B
CLASS="FUNCTION"
>array()</B
></A
> command for associative arrays.
      These two snippets of code fill up the one-dimensional array in
      the same way:

     <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> 
# Example 1:

$a["color"]	= "red";
$a["taste"]	= "sweet";
$a["shape"]	= "round";
$a["name"]	= "apple";
$a[3]		= 4;


# Example 2:
$a = array(
     "color" =&#62; "red",
     "taste" =&#62; "sweet",
     "shape" =&#62; "round",
     "name"  =&#62; "apple",
     3       =&#62; 4
);
      </PRE
><P
></P
></DIV
>

     </P
><P
>      The <A
HREF="function.array.html"
><B
CLASS="FUNCTION"
>array()</B
></A
> function can be nested for 
      multi-dimensional arrays:

     <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> 
&lt;?
$a = array(
     "apple"  =&#62; array(
          "color"  =&#62; "red",
          "taste"  =&#62; "sweet",
          "shape"  =&#62; "round"
     ),
     "orange"  =&#62; array(
          "color"  =&#62; "orange",
          "taste"  =&#62; "sweet",
          "shape"  =&#62; "round"
     ),
     "banana"  =&#62; array(
          "color"  =&#62; "yellow",
          "taste"  =&#62; "paste-y",
          "shape"  =&#62; "banana-shaped"
     )
);

echo $a["apple"]["taste"];    # will output "sweet"
?&#62;
      </PRE
><P
></P
></DIV
>

   </P
></DIV
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="TYPES.OBJECT"
>Objects</A
></H2
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="TYPES.OBJECT.INIT"
>Object Initialization</A
></H3
><P
>      To initialize an object, you use the new statement to instantiate
      the object to a variable.

      <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
>class foo {
    function do_foo () { 
        echo "Doing foo."; 
    }
}

$bar = new foo;
$bar -&#62; do_foo ();
       </PRE
><P
></P
></DIV
>

  </P
></DIV
></DIV
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