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><A
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>array_map</H1
><DIV
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><A
NAME="AEN7627"
></A
><P
> (PHP 4 >= 4.0.6)</P
>array_map --
Applies the callback to the elements of the given arrays
</DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN7630"
></A
><H2
>Description</H2
>array <B
CLASS="methodname"
>array_map</B
> ( callback function, array arr1 [, array arr2...])<BR
></BR
><P
> <B
CLASS="function"
>array_map()</B
> returns an array containing all
the elements of <TT
CLASS="parameter"
><I
>arr1</I
></TT
> after applying the
callback <TT
CLASS="parameter"
><I
>function</I
></TT
> to each one.
The number of parameters that the callback
<TT
CLASS="parameter"
><I
>function</I
></TT
> accepts
should match the number of arrays
passed to the <B
CLASS="function"
>array_map()</B
>
</P
><P
> <TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN7651"
></A
><P
><B
>Example 1. <B
CLASS="function"
>array_map()</B
> example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="php"
><?php
function cube($n) {
return $n*$n*$n;
}
$a = array(1, 2, 3, 4, 5);
$b = array_map("cube", $a);
print_r($b);
?></PRE
></TD
></TR
></TABLE
><P
> This makes <TT
CLASS="varname"
>$b</TT
> have:
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="screen"
>Array
(
[0] => 1
[1] => 8
[2] => 27
[3] => 64
[4] => 125
)</PRE
></TD
></TR
></TABLE
>
</P
></DIV
></TD
></TR
></TABLE
>
</P
><P
> <TABLE
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CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN7659"
></A
><P
><B
>Example 2. <B
CLASS="function"
>array_map()</B
> - using more arrays</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="php"
><?php
function show_Spanish($n, $m) {
return "The number $n is called $m in Spanish";
}
function map_Spanish($n, $m) {
return array ($n => $m);
}
$a = array(1, 2, 3, 4, 5);
$b = array("uno", "dos", "tres", "cuatro", "cinco");
$c = array_map("show_Spanish", $a, $b);
print_r($c);
$d = array_map("map_Spanish", $a , $b);
print_r($d);
?></PRE
></TD
></TR
></TABLE
><P
> This results:
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="screen"
>// printout of $c
Array
(
[0] => The number 1 is called uno in Spanish
[1] => The number 2 is called dos in Spanish
[2] => The number 3 is called tres in Spanish
[3] => The number 4 is called cuatro in Spanish
[4] => The number 5 is called cinco in Spanish
)
// printout of $d
Array
(
[0] => Array
(
[1] => uno
)
[1] => Array
(
[2] => dos
)
[2] => Array
(
[3] => tres
)
[3] => Array
(
[4] => cuatro
)
[4] => Array
(
[5] => cinco
)
)</PRE
></TD
></TR
></TABLE
>
</P
></DIV
></TD
></TR
></TABLE
>
</P
><P
> Usually when using two or more arrays, they should be of equal length
because the callback function is applied in parallel to the corresponding
elements.
If the arrays are of unequal length, the shortest one will be extended
with empty elements.
</P
><P
> An interesting use of this function is to construct an array of arrays,
which can be easily performed by using <TT
CLASS="constant"
><B
>NULL</B
></TT
>
as the name of the callback function
</P
><P
> <TABLE
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BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN7669"
></A
><P
><B
>Example 3. Creating an array of arrays</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="php"
><?php
$a = array(1, 2, 3, 4, 5);
$b = array("one", "two", "three", "four", "five");
$c = array("uno", "dos", "tres", "cuatro", "cinco");
$d = array_map(null, $a, $b, $c);
print_r($d);
?></PRE
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
>
</P
><P
> The printout of the program above will be:
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="screen"
>Array
(
[0] => Array
(
[0] => 1
[1] => one
[2] => uno
)
[1] => Array
(
[0] => 2
[1] => two
[2] => dos
)
[2] => Array
(
[0] => 3
[1] => three
[2] => tres
)
[3] => Array
(
[0] => 4
[1] => four
[2] => cuatro
)
[4] => Array
(
[0] => 5
[1] => five
[2] => cinco
)
)</PRE
></TD
></TR
></TABLE
>
</P
><P
> See also <A
HREF="function.array-filter.html"
><B
CLASS="function"
>array_filter()</B
></A
>,
<A
HREF="function.array-reduce.html"
><B
CLASS="function"
>array_reduce()</B
></A
>, and
<A
HREF="function.array-walk.html"
><B
CLASS="function"
>array_walk()</B
></A
>.
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