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

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

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><H1
><A
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>usort</H1
><DIV
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><A
NAME="AEN9336"
></A
><P
>    (PHP 3&#62;= 3.0.3, PHP 4 )</P
>usort&nbsp;--&nbsp;
     Sort an array by values using a user-defined comparison function
    </DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN9339"
></A
><H2
>Description</H2
>void <B
CLASS="methodname"
>usort</B
> ( array array, callback cmp_function)<BR
></BR
><P
>&#13;     This function will sort an array by its values using a
     user-supplied comparison function.  If the array you wish to sort
     needs to be sorted by some non-trivial criteria, you should use
     this function.
    </P
><P
>&#13;     The comparison function must return an integer less than, equal
     to, or greater than zero if the first argument is considered to
     be respectively less than, equal to, or greater than the
     second. 
     <DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
       If two members compare as equal, their order in the sorted array is undefined.
       Up to PHP 4.0.6 the user defined functions would keep the original order for
       those elements, but with the new sort algorithm intruduced with 4.1.0 this
       is no longer the case as there is no solution to do so in an efficient way.
      </P
></BLOCKQUOTE
></DIV
>
    </P
><P
>&#13;     <TABLE
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><TR
><TD
><DIV
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><A
NAME="AEN9355"
></A
><P
><B
>Example 1. <B
CLASS="function"
>usort()</B
> example</B
></P
><TABLE
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><TD
><PRE
CLASS="php"
>function cmp ($a, $b) {
    if ($a == $b) return 0;
    return ($a &#62; $b) ? -1 : 1;
}

$a = array (3, 2, 5, 6, 1);

usort ($a, "cmp");

while (list ($key, $value) = each ($a)) {
    echo "$key: $value\n";
}</PRE
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
>
    </P
><P
>&#13;     This example would display:
    </P
><P
>&#13;     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="screen"
>0: 6
1: 5
2: 3
3: 2
4: 1</PRE
></TD
></TR
></TABLE
>
    </P
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
      Obviously in this trivial case the <A
HREF="function.rsort.html"
><B
CLASS="function"
>rsort()</B
></A
>
      function would be more appropriate.
     </P
></BLOCKQUOTE
></DIV
><P
>&#13;     <TABLE
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><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN9366"
></A
><P
><B
>Example 2. 
       <B
CLASS="function"
>usort()</B
> example using multi-dimensional array
      </B
></P
><TABLE
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><TR
><TD
><PRE
CLASS="php"
>function cmp ($a, $b) {
    return strcmp($a["fruit"], $b["fruit"]);
}

$fruits[0]["fruit"] = "lemons";
$fruits[1]["fruit"] = "apples";
$fruits[2]["fruit"] = "grapes";

usort($fruits, "cmp");

while (list ($key, $value) = each ($fruits)) {
    echo "\$fruits[$key]: " . $value["fruit"] . "\n";
}</PRE
></TD
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></DIV
></TD
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>
    </P
><P
>&#13;     When sorting a multi-dimensional array, $a and $b contain
     references to the first index of the array.
    </P
><P
>&#13;     This example would display:
    </P
><P
>&#13;     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="screen"
>$fruits[0]: apples
$fruits[1]: grapes
$fruits[2]: lemons</PRE
></TD
></TR
></TABLE
>
    </P
><P
>&#13;     <TABLE
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CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN9375"
></A
><P
><B
>Example 3. 
       <B
CLASS="function"
>usort()</B
> example using a member function of an object
      </B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="php"
>class TestObj {
    var $name;

    function TestObj($name)
    {
        $this-&#62;name = $name;
    }

    /* This is the static comparing function: */
    function cmp_obj($a, $b)
    {
        $al = strtolower($a-&#62;name);
        $bl = strtolower($b-&#62;name);
        if ($al == $bl) return 0;
        return ($al &#62; $bl) ? +1 : -1;
    }
}

$a[] = new TestObj("c");
$a[] = new TestObj("b");
$a[] = new TestObj("d");

uasort($a, array ("TestObj", "cmp_obj"));

foreach ($a as $item) {
    print $item-&#62;name."\n";
}</PRE
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
>
    </P
><P
>&#13;     This example would display:
    </P
><P
>&#13;     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="screen"
>b
c
d</PRE
></TD
></TR
></TABLE
>
    </P
><P
>&#13;     See also <A
HREF="function.uasort.html"
><B
CLASS="function"
>uasort()</B
></A
>,
     <A
HREF="function.uksort.html"
><B
CLASS="function"
>uksort()</B
></A
>, <A
HREF="function.sort.html"
><B
CLASS="function"
>sort()</B
></A
>,
     <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.natsort.html"
><B
CLASS="function"
>natsort()</B
></A
>, and <A
HREF="function.rsort.html"
><B
CLASS="function"
>rsort()</B
></A
>.
    </P
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