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max

(PHP 4, PHP 5, PHP 7, PHP 8)

maxBestimmt den Maximalwert

Beschreibung

max(mixed $value, mixed ...$values): mixed

Alternative Signatur (wird bei benannten Argumenten nicht unterstützt):

max(array $value_array): mixed

Ist der erste und einzige Parameter ein Array, gibt max() den größten Wert dieses Arrays zurück. Werden mindestens zwei Parameter übergeben, gibt max() den größeren dieser Werte zurück.

Hinweis:

Werte unterschiedlichen Typs werden unter Verwendung der Standard-Vergleichsregeln verglichen. Zum Beispiel wird ein nichtnumerischer string mit einem int verglichen, als ob er 0 wäre, aber mehrere nichtnumerische string-Werte werden alphanumerisch verglichen. Der tatsächlich zurückgegebene Wert ist vom ursprünglichen Typ ohne angewandte Umwandlung.

Achtung

Vorsicht ist geboten, wenn Argumente verschiedenen Typs übergeben werden, da max() in diesem Fall unvorhersehbare Ergebnisse liefert.

Parameter-Liste

value

Ein vergleichbarer Wert.

values

Jegliche vergleichbaren Werte.

value_array

Ein Array, das Werte enthält.

Rückgabewerte

max() gibt den gemäß den Standard-Vergleichen als "größten" angesehenen Parameter-Wert zurück. Evaluieren mehrere Werte unterschiedlichen Typs als gleich (z.B. 0 und 'abc'), wird der zuerst übergebene zurückgegeben.

Wird ein leeres Array übergeben, gibt die Funktion false zurück und löst einen E_WARNING-Fehler aus.

Beispiele

Beispiel #1 Beispiel für die Verwendung von max()

<?php
echo max(23167);  // 7
echo max(array(245)); // 5

// Die Zeichenkette 'hallo' wird wie 0 behandelt, wenn sie mit einem Int verglichen wird
// Da die beiden Werte gleich sind, bestimmt die Reihenfolge der Übergabe das Ergebnis
echo max(0'hallo');     // 0
echo max('hallo'0);     // hallo

// Hier vergleichen wir -1 < 0, sodass 'hallo' der größte Wert ist
echo max('hallo', -1);    // hallo

// Bei mehreren Arrays unterschiedlicher Länge, gibt max das längste zurück
$val max(array(222), array(1111)); // array(1, 1, 1, 1)

// Mehrere Arrays gleicher Länge werden von links nach rechts verglichen,
// daher ist in unserem Beispiel 2 == 2, aber 5 > 4
$val max(array(248), array(251)); // array(2, 5, 1)

// Sind ein Array und ein Nicht-Array-Parameter gegeben, wird das Array zurückgegeben,
// da Vergleiche Arrays als größer behandeln als alle anderen Werte
$val max('string', array(257), 42);   // array(2, 5, 7)

// Ist ein Argument NULL oder ein boolescher Wert, wird es mit anderen Werten
// unter Verwendung der Regel FALSE < TRUE verglichen, ohne Rücksicht auf die anderen beteiligten Typen
// Im folgenden Beispiel wird -10 im Vergleich wie TRUE behandelt
$val max(-10FALSE); // -10

// Andererseits wird 0 wie FALSE behandelt, so dass es "kleiner" ist als TRUE
$val max(0TRUE); // TRUE
?>

Siehe auch

  • min() - Bestimmt den Minimalwert
  • count() - Zählt alle Elemente eines Arrays oder etwas in einem Objekt

add a note add a note

User Contributed Notes 18 notes

up
47
keith at bifugi dot com
5 years ago
The simplest way to get around the fact that max() won't give the key is array_search:

<?php
$student_grades
= array ("john" => 100, "sarah" => 90, "anne" => 100);
$top_student = array_search(max($student_grades),$student_grades); // john
?>

This could also be done with array_flip, though overwriting will mean that it gets the last max value rather than the first:

<?php
$grades_index
= array_flip($student_grades);
$top_student = $grades_index[max($student_grades)]; // anne
?>

To get all the max value keys:

<?php
$top_students
= array_keys($student_grades,max($student_grades)); // john, anne
?>
up
8
ries at vantwisk dot nl
12 years ago
I had several occasions that using max is a lot slower then using a if/then/else construct. Be sure to check this in your routines!

Ries
up
11
volch5 at gmail dot com
7 years ago
max() (and min()) on DateTime objects compares them like dates (with timezone info) and returns DateTime object.
<?php
$dt1
= new DateTime('2014-05-07 18:53', new DateTimeZone('Europe/Kiev'));
$dt2 = new DateTime('2014-05-07 16:53', new DateTimeZone('UTC'));
echo
max($dt1,$dt2)->format(DateTime::RFC3339) . PHP_EOL; // 2014-05-07T16:53:00+00:00
echo min($dt1,$dt2)->format(DateTime::RFC3339) . PHP_EOL; // 2014-05-07T18:53:00+03:00
?>

It works at least 5.3.3-7+squeeze17
up
13
Alex Rath
11 years ago
Notice that whenever there is a Number in front of the String, it will be used for Comparison.

<?php

  max
('7iuwmssuxue', 1); //returns 7iuwmssuxu
 
max('-7suidha', -4); //returns -4

?>

But just if it is in front of the String

<?php

  max
('sdihatewin7wduiw', 3); //returns 3

?>
up
14
costinu
9 years ago
max(null, 0) = null
max(0, null) = 0
up
8
ReVo_
7 years ago
Sometimes you could need to get the max from an array which looks like this:

<?php
$arrTest
= array(
    array(
"day" => 1, "b" => 10 ),
    array(
"day" => 2, "b" => 43 ),
    array(
"day" => 3, "b" => 2 ),
    array(
"day" => 4, "b" => -3 ),
    array(
"day" => 5, "b" => 4 ),
    array(
"day" => 6, "b" => -5 )
);
?>
all max functions i see around don't provide a way to get the max value of the values in (example) key "b"

<?php
function maxValueInArray($array, $keyToSearch)
{
   
$currentMax = NULL;
    foreach(
$array as $arr)
    {
        foreach(
$arr as $key => $value)
        {
            if (
$key == $keyToSearch && ($value >= $currentMax))
            {
               
$currentMax = $value;
            }
        }
    }

    return
$currentMax;
}

//                                            array       key
$value = maxValueInArray($arrTest, "b");

?>

output: 43
up
2
michaelangel0 at mail.com
14 years ago
Matlab users and others may feel lonely without the double argument output from min and max functions.

To have the INDEX of the highest value in an array, as well as the value itself, use the following, or a derivative:

<?php
function doublemax($mylist){
 
$maxvalue=max($mylist);
  while(list(
$key,$value)=each($mylist)){
    if(
$value==$maxvalue)$maxindex=$key;
  }
  return array(
"m"=>$maxvalue,"i"=>$maxindex);
}
?>
up
2
marcini
12 years ago
Note that max() can compare dates, so if you write something like this:

<?php
$dates
= array('2009-02-15', '2009-03-15');
echo
max($dates);
?>

you will get: 2009-03-15.
up
1
johnphayes at gmail dot com
15 years ago
Regarding boolean parameters in min() and max():

(a) If any of your parameters is boolean, max and min will cast the rest of them to boolean to do the comparison.
(b) true > false
(c) However, max and min will return the actual parameter value that wins the comparison (not the cast).

Here's some test cases to illustrate:

1.  max(true,100)=true
2.  max(true,0)=true
3.  max(100,true)=100
4.  max(false,100)=100
5.  max(100,false)=100
6.  min(true,100)=true
7.  min(true,0)=0
8.  min(100,true)=100
9.  min(false,100)=false
10. min(100,false)=false
11. min(true,false)=false
12. max(true,false)=true
up
1
php at rijkvanwel dot nl
10 years ago
To get the largest key in an array:

<?php
$array
= array( 0 => 'first', 1=> 'second', /* ... */ 99 => 'nth' );
$max_key = max( array_keys( $array ) ); // 99
?>
up
0
chris at candm dt org dt uk
3 months ago
A function to return the key of the max value of an array. For multiple max values, it will return the key of first. Change > to >= to get the last.

function array_max_key($arr) {
    $maxkey='';
    $maxval=false;
    array_walk($arr,
        function (&$cval,&$ckey) use(&$maxkey,&$maxval) {
            if ($maxval === false || $cval > $maxval) {
                $maxval = $cval;
                $maxkey = $ckey;
            }
        }
    );
    return $maxkey;
}
up
1
sun at drupal dot org
10 years ago
Note that max() throws a warning if the array is empty:

<?php
$a
= array();
max($a);
// Warning: max(): Array must contain at least one element
?>

So make sure your data isn't empty.
up
1
harmor
13 years ago
A way to bound a integer between two values is:

<?php
function bound($x, $min, $max)
{
     return
min(max($x, $min), $max);
}
?>

which is the same as:

<?php
$tmp
= $x;
if(
$tmp < $min)
{
   
$tmp = $min;
}
if(
$tmp > $max)
{
    
$tmp = $max;
}
$y = $tmp;
?>

So if you wanted to bound an integer between 1 and 12 for example:

Input:
<?php
$x
= 0;
echo
bound(0, 1, 12).'<br />';
$x = 1;
echo
bound($x, 1, 12).'<br />';
$x = 6;
echo
bound($x, 1, 12).'<br />';
$x = 12;
echo
bound($x, 1, 12).'<br />';
$x = 13;
echo
bound($x, 1, 12).'<br />';
?>

Output:
1
1
6
12
12
up
-1
info at osworx dot net
2 years ago
Be aware if a array like this is used (e.g. values from a shopping cart):
<?php
Array
(
    [
0] => 142,80
   
[1] => 39,27
   
[2] => 22,80
   
[3] => 175,80
)?>
The result will be: 39,27 and not - as expected - 175,80

So, to find the max value, use integer only like:
<?php
Array
(
    [
0] => 14280
   
[1] => 3927
   
[2] => 2280
   
[3] => 17580
)?>
and you will get the correct result: 17580
up
-3
levim at php dot net
9 years ago
<?php
/**
* @param array $array
*
* @return int|null Returns the largest value of the array. Returns NULL if no
*     integers are found.
*/
function array_max_recursive(array $array) {
   
$max = NULL;
   
$stack = array($array);

    do {
       
$current = array_pop($stack );
        foreach (
$current as $value) {
            if (
is_array($value)) {
               
$stack[] = $value;
            } elseif (
filter_var($value, FILTER_VALIDATE_INT) !== FALSE) {
               
// max(NULL, 0) returns NULL, so cast it
               
$max = (int) max($max, $value);
            }
        }

    } while (!empty(
$stack));

    return
$max;
}
?>

- This function is not actually recursive, but fulfills the requirement that it works on sub-arrays.  I do this because PHP is not very good at recursion.  I also did it because I enjoy doing things this way. 
- It returns something of type int, never a string representation of an int. The exception is when you provide an array that does not contain any integers.  It will then return NULL.
- It ignores non-array, non-int values.
up
-4
toon dot baeyens at gmail dot com
9 years ago
A little function for multi-dimensional arrays:
<?php
function amax($array){
    if(
is_array($array)){
        foreach(
$array as $key => $value){
           
$array[$key] = amax($value);
        }
        return
max($array);
    }else{
        return
$array;
    }
}
?>
up
-2
blackmac01 at gmail dot com
2 years ago
In response to: keith at bifugi dot com

If you want to find the specific key(s) that match the maximum value in an array where the values may be duplicated, you can loop through and perform a simple check:
<?php

# Example Array
$a = array(
    
'key1' => 100,
    
'key2' => 90,
    
'key3' => 100,
    
'key4' => 90,
);

# First get the maximum value
$max = max($a);

# Create a new array containing all keys which have the max value
foreach($a as $key => $val) {    
     if(
$val === $max) $b[] = $key;
}

# If you want a string list, just do this
$b = implode(' ', $b);
?>

This produces consistent results and will scale well in terms of performance, whereas functions like array_search and array_flip can lead to degraded performance when dealing with large amounts of data.
up
-7
Michael Blinn
2 years ago
Be careful using max() with objects, as it returns a reference not a new object.

<?php

$min_date
= date_create('2019-03-05');
$max_date = date_create('2019-03-06');

$date_by_reference = max($min_date, $max_date);

// $date_by_reference and $max_date are now the same object

echo '$max_date is ' . date_format($max_date, 'Y-m-d') . PHP_EOL; // '2019-03-06'
echo '$date_by_reference is ' . date_format($date_by_reference, 'Y-m-d') . PHP_EOL; // '2019-03-06'

date_add($date_by_reference, date_interval_create_from_date_string('1 days')); // Add 1 day to $date_by_reference, changes $max_date too

echo '$max_date is changed ' . date_format($max_date, 'Y-m-d') . PHP_EOL; // '2019-03-07'
echo '$date_by_reference is changed ' . date_format($date_by_reference, 'Y-m-d') . PHP_EOL; // '2019-03-07'

?>
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