SunshinePHP Developer Conference 2015

max

(PHP 4, PHP 5)

maxFind highest value

Description

mixed max ( array $values )
mixed max ( mixed $value1 , mixed $value2 [, mixed $value3... ] )

If the first and only parameter is an array, max() returns the highest value in that array. If at least two parameters are provided, max() returns the biggest of these values.

Note:

PHP will evaluate a non-numeric string as 0 if compared to integer, but still return the string if it's seen as the numerically highest value. If multiple arguments evaluate to 0, max() will return a numeric 0 if given, else the alphabetical highest string value will be returned.

Parameters

values

An array containing the values.

Return Values

max() returns the numerically highest of the parameter values. If multiple values can be considered of the same size, the one that is listed first will be returned.

When max() is given multiple arrays, the longest array is returned. If all the arrays have the same length, max() will use lexicographic ordering to find the return value.

When given a string it will be cast as an integer when comparing.

Examples

Example #1 Example uses of max()

<?php
echo max(13567);  // 7
echo max(array(245)); // 5

// When 'hello' is cast as integer it will be 0. Both the parameters are equally
// long, so the order they are given in determines the result
echo max(0'hello');     // 0
echo max('hello'0);     // hello

echo max('42'3); // '42'

// Here 0 > -1, so 'hello' is the return value.
echo max(-1'hello');    // hello

// With multiple arrays of different lengths, max returns the longest
$val max(array(222), array(1111)); // array(1, 1, 1, 1)

// With multiple arrays of the same length, max compares from left to right
// using lexicographic order, so in our example: 2 == 2, but 4 < 5
$val max(array(248), array(257)); // array(2, 5, 7)

// If both an array and non-array are given, the array
// is always returned as it's seen as the largest
$val max('string', array(257), 42);   // array(2, 5, 7)
?>

See Also

  • min() - Find lowest value
  • count() - Count all elements in an array, or something in an object

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User Contributed Notes 18 notes

up
8
costinu
2 years ago
max(null, 0) = null
max(0, null) = 0
up
4
Alex Rath
4 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
5
michaelangel0 at mail.com
7 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
5
marcini
5 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
3
johnphayes at gmail dot com
8 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
4
php at rijkvanwel dot nl
3 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
2
harmor
6 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
2
levim at php dot net
2 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
1
sun at drupal dot org
3 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
toon dot baeyens at gmail dot com
2 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
volch5 at gmail dot com
5 months 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
0
ReVo_
4 months 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
0
grillen at abendstille dot at
4 years ago
max only accepts not empty arrays.

if you work a lot with numerical arrays and with max, this function may come in handy:

<?php
if (!function_exists('emax')) {
    function
emax($arr) {
        if (!
is_array($arr)) return call_user_func_array('max', func_get_args());
        if (
count($arr) == 0) return 0;
        return
max($arr);
    }
}
?>
up
0
ries at vantwisk dot nl
5 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
0
Marcus Zacco
6 years ago
This code loops through seven arrays and finds the highest average value within those arrays - and changes the font color for it. Great for highlighting.

The biggest take-away is this the row
if($average[$i] == max($average))

The number_format just rounds the numbers to 0 decimal points.

<?php
for ( $i = 0; $i <= 6; $i++) {
 
$num = $i+1;
  if(
$average[$i] == max($average)) {
    echo
"Value ".$num.": <font color='red'>".number_format($average[$i], 0, '.', '')." % </font<br>";
  } else {
    echo
"Value ".$num.": ".number_format($average[$i],0,'.','')." %<br>";
  }
}
?>

### OUTPUT

Value 1: 52 %
Value 2: 58 %
Value 3: 56 %
Value 4: 73 %
Value 5: 77 % <- this 77 is highlighted in red
Value 6: 71 %
Value 7: 75 %
up
0
johnmott59 at hotmail dot com
7 years ago
To find the maximum value from a set of 1-dimensional arrays, do this:

<?php
$d1
= array(450,420,440,430,421);
$d2 = array(460,410,410,430,413,375,256,411,656);
$d3 = array(430,440,470,435,434,255,198);

$t = max(max($d1),max($d2),max($d3));
// $t is 656
?>

The inner max() functions operate on the arrays, the outer max compares the numeric results of the inner ones.
up
-1
Alex Stanhope
3 years ago
If you want to test whether x lies within two bounds:

<?php
   
static function isInRange($x, $y1, $y2) {
        return( (
$x >= min($y1, $y2)) && ($x <= max($y1, $y2)) );
    }

//called by:

  
class::isInRange(10,12,2);
//or
  
$this->isInRange(10,12,2);
//or (drop static)
  
isInRange(10,12,2);

//simple test function:

   
static function unit_isInRange() {
       
$output = array();
       
$inputlist[] = array(10, 12, 2, true);
       
$inputlist[] = array(13, 12, 2, false);
       
$inputlist[] = array(2, -2, 2, true);
       
$inputlist[] = array(2, -8, -2, false);
        foreach(
$inputlist as $input) {
           
$output[] = array(
               
'input' => array($input[0], $input[1], $input[2]),
               
'output' => self::isInRange($input[0],$input[1],$input[2]),
               
'expected' => $input[3],
            );
        }
        return(
$output);
    }
?>
up
-1
jeremi23 at gmail dot com
7 years ago
max on a an array with key/values

<?php
$tmp
= array(1 => 5, 2=> 3);
echo
max($tmp);
?>

this return 5, so the max is done on the values.
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