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max

(PHP 4, PHP 5)

maxНаходит наибольшее значение

Описание

mixed max ( number $arg1 , number $arg2 [, number $... ] )
mixed max ( array $numbers )

Возвращает наибольшее из предложенных чисел.

Если в качестве аргументов передан только один - массив чисел, max() возвращает наибольшее из них. Если первый аргумент - integer или float, то обязательно должен быть хотя бы ещё один. В этом случае функция вернёт наибольшее из них. Можно сравнивать неограниченное количество чисел.

Замечание: PHP считает строку, которую не удалось преобразовать в число, как 0, но вернёт саму строку, в случае, если все остальные числа отрицательные. Если указано несколько элементов, эквивалентных 0, max() вернёт первый из них (самый левый).

Пример #1 Примеры использования max()

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

echo max(0'hello');     // 0
echo max('hello'0);     // hello
echo max(-1'hello');    // hello

// При указании нескольких массивов, они сравниваются полностью
// в нашем примере: 2 == 2, но 4 < 5
$val max(array(248), array(257)); // array(2, 5, 7)

// При указании массива и отдельных чисел,
// всегда возвращается массив, т.к. он считается самым большим
$val max('string', array(257), 42);   // array(2, 5, 7)
?>

См также min() и count().


User Contributed Notes
max
dan at coders dot co dot nz
23-May-2010 06:29
max() on undefined parameters does not assume the value is zero, it ignores it.
<?php
$dimensions
= array('left' => -2);
// If $dimensions['right'] was never set,
// we may expect it to be treated as zero, but
print max($dimensions['left'], $dimensions['right']);
//
// Returns -2, not zero

print max(0+$dimensions['left'], 0+$dimensions['right']);
?>
would be a work-around, but it's probably tidier to ensure your values are set correctly first.

(on PHP 5.2.11 anyway)
Alex Rath
10-Apr-2010 06:27
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

?>
grillen at abendstille dot at
02-Apr-2010 11:55
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);
    }
}
?>
artem dot yagutyan at gmail dot com
27-Mar-2010 11:28
This Is Good Example: For max to min

<?php

function max_key($array) {
foreach (
$array as $key => $val) {
    if (
$val == max($array)) return $key;
    }
}

$array = array(10, 2, 5, 7, 4,15,32,8,41,25);
$array_count=count($array);   
for(
$i=1;$i<=$array_count;$i++){
   
$max_val[$i]=max_key($array);
   
   
$view=$array[$max_val[$i]];
       
    unset(
$array[$max_val[$i]]);
       
       
    print
$view."<br />"; //
}

/* OUTPUT
41 // Max
32
25
15
10
8
7
5
4
2 //Min
*/

?>
marcini
11-May-2009 02:34
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.
ries at vantwisk dot nl
09-Nov-2008 02:36
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
Marcus Zacco
29-Sep-2008 04:47
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 %
henk at tobbe dot net dot au
16-Apr-2008 07:05
In a publication by WROX I noted a variant of the earlier "bound" function:

A parameter had to be between 1 and 3...

$par=round((min(max($x,1),3));
stuff at necr0manzer dot de
03-Mar-2008 07:11
mick at wireframe dot com's solution to finding the key for the highest value didn't work for me, so I wrote one myself:

<?php
function max_key($array) {
    foreach (
$array as $key => $val) {
        if (
$val == max($array)) return $key;
    }
}

$array = array(1, 2, 5, 7, 4);
echo
max($array); // 7
echo max_key($array); // 3
?>

of course this also works with associative arrays, but it will only return a single result!
harmor
21-Feb-2008 05:56
A way to bound a integer between two values is:

function bound($x, $min, $max)
{
     return min(max($x, $min), $max);
}

which is the same as:

$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:
$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
mick at wireframe dot com
30-Oct-2007 11:51
There are a couple of things you can do for cleaner code if you want the keys returned from the array. I am not sure how they each impact performance, but the visual readability is more beneficial for me -- your mileage may vary.

In the first example keys and max value is returned:

<?php
// First, let's pretend we have an array like this:
$Some_Array = array(
 
'john' => 40,
 
'susan' => 40,
 
'jane' => 24,
 
'michael' => 19,
 
'jimmy' => 38
);

function
max_extract($My_Array) {

 
$Max_Value = max($My_Array);
  return
array_fill_keys(array_keys($My_Array, $Max_Value), $Max_Value);

}
// ! max_extract()
?>

Or, if you are only interested in the keys and don't care what the max is:

<?php
function max_extract($My_Array) {

  return
array_keys($My_Array, max($My_Array));
 
// You can also array_flip() this is you want them as keys
  // or if some other reason makes this relevant/needed.

} // ! max_extract()
?>

There are many possible variations when using the search parameter of array_keys() along with other array functions.
sta
07-Sep-2007 04:05
Or to take multiple maximum values into consideration:

function doublemax($mylist){
    $maxvalue=max($mylist);
    $max_keys = array();
   
        while(list($key,$value)=each($mylist)){
        if($value==$maxvalue)
        array_push($max_keys,$key);
    }
    return $max_keys;
}
joan dot codina at upf dot edu
14-Jul-2007 05:11
This is highly ineficient, but can be a bit better

<?
function doublemax($mylist){
 
$maxvalue=max($mylist);
  while(list(
$key,$value)=each($mylist)){
     if(
$value==$maxvalue)
    return array(
"key"=>$key,"value"=>$value);
  }
}
?>
michaelangel0 at mail.com
04-Jul-2007 10:00
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:

<?
function doublemax($mylist){
 
$maxvalue=max($mylist);
  while(list(
$key,$value)=each($mylist)){
    if(
$value==$maxvalue)$maxindex=$key;
  }
  return array(
"m"=>$maxvalue,"i"=>$maxindex);
}
?>
jeremi23 at gmail dot com
14-Jun-2007 10:09
max on a an array with key/values

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

this return 5, so the max is done on the values.
johnmott59 at hotmail dot com
17-May-2007 07:35
To find the maximum value from a set of 1-dimensional arrays, do this:

$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.
johnphayes at gmail dot com
02-May-2006 04:27
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
tim at (NOSPAM) dot crazynot2 dot com
08-Nov-2005 09:56
In response to the previous two posters (zher0 at netcarrier dot com & walkingmantis):

I was trying to do exactly what zher0 suggested; calculate the max value of a multi-dimensional array with variably sized 'sub-arrays'.  Here is a simple little function I came up with to do just that:

<?php
function multimax( $array ) {
   
// use foreach to iterate over our input array.
   
foreach( $array as $value ) {
       
       
// check if $value is an array...
       
if( is_array($value) ) {
           
           
// ... $value is an array so recursively pass it into multimax() to
            // determine it's highest value.
           
$subvalue = multimax($value);
           
           
// if the returned $subvalue is greater than our current highest value,
            // set it as our $return value.
           
if( $subvalue > $return ) {
               
$return = $subvalue;
            }
       
        } elseif(
$value > $return) {
           
// ... $value is not an array so set the return variable if it's greater
            // than our highest value so far.
           
$return = $value;
        }
    }
   
   
// return (what should be) the highest value from any dimension.
   
return $return;
}
?>

Please note that I have only performed very limited testing on this code -- be sure to check it thoroughly if you implement it somewhere!
nonick AT 8027 DOT org
17-Dec-2003 03:50
If you are working with numbers, then you can use:

    $a = ($b > $c) ? $b : $c;

which is somewhat faster (roughly 16%) than

    $a = max($b, $c);

I tested this on several loops using integers and floats, over 1 million iterations.

I'm running PHP 4.3.1 as a module for Apache 1.3.27.
mikhail_kovalev at mail dot ru
13-May-2003 11:32
Note that in version 4.0.3 (the only version I tested):

max (0, 0); // returns 0.
max (0, false); // returns 0.
max (false, 0); // returns false.
max (false, false); // returns false.

As a solution use this:

(int) max (false, 0); // returns 0.
(int) max (false, false); // returns 0.
 

 
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