PHP Australia Conference 2015

min

(PHP 4, PHP 5)

minTrova il valore minimo

Descrizione

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

min() restituisce il numericamente più piccolo dei valori dati come parametro.

Se il primo ed unico pareametro è un array, la funzione min() restituisce il valore più basso nell'array. Se il primo parametro è un intero, una stringa, o un float, occorrono almeno due parametri e min() restituisce il minore tra questi. Si può confrontare un numero illimitato di valori.

Nota:

Le stringhe non numeriche saranno considerate dal PHP come 0, ma verrà restituita la stringa se questa è il più basso valore numerico. Se vi sono più argomenti considerati come 0, la funzione min() restituirà il primo (il valore più a sinistra).

Example #1 Esempio di uso di min()

<?php
echo min(23167);  // 1
echo min(array(245)); // 2

echo min(0'hello');     // 0
echo min('hello'0);     // hello
echo min('hello', -1);    // -1

// Con diversi array, min confronta da sinistra a destra
// quindi nell'esempio: 2 == 2, e 4 < 5
$val min(array(248), array(251)); // array(2, 4, 8)

// In caso di parametri misti array e non array, l'array non sarà mai restituito
// perché considerato il più grande
$val min('string', array(257), 42);   // string
?>

Vedere anche max() e count().

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User Contributed Notes 16 notes

up
3
Teelevision
11 months ago
A function that returns the lowest integer that is not 0.
<?php
/* like min(), but casts to int and ignores 0 */
function min_not_null(Array $values) {
    return
min(array_diff(array_map('intval', $values), array(0)));
}
?>
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5
DO
6 years ago
I've modified the bugfree min-version to ignore NULL values (else it returns 0).

<?php
function min_mod () {
 
$args = func_get_args();

  if (!
count($args[0])) return false;
  else {
   
$min = false;
    foreach (
$args[0] AS $value) {
      if (
is_numeric($value)) {
       
$curval = floatval($value);
        if (
$curval < $min || $min === false) $min = $curval;
      }
    }
  }

  return
$min;  
}
?>
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4
php at keith tyler dot com
3 years ago
If NAN is the first argument to min(), the second argument will always be returned.

If NAN is the second argument, NAN will always be returned.

The relationship is the same but inverted for max().

<?php
// \n's skipped for brevity
print max(0,NAN);
print
max(NAN,0);
print
min(0,NAN);
print
min(NAN,0);
?>

Returns:
0
NAN
NAN
0
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3
alx5000 at walla dot com
9 years ago
If you want min to return zero (0) when comparing to a string, try this:

<?php
min
(3,4,";");  // ";"
min(0,min(3,4,";")) // 0
?>
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2
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
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2
harmor
6 years ago
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
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1
nonick AT 8027 DOT org
10 years ago
I tested this with max(), but I suppose it applies to min() too: If you are working with numbers, then you can use:

    $a = ($b < $c) ? $b : $c;

which is somewhat faster (roughly 16%) than

    $a = min($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.
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2
Anonymous
8 years ago
NEVER EVER use this function with boolean variables !!!
Or you'll get something like this: min(true, 1, -2) == true;

Just because of:
min(true, 1, -2) == min(min(true,1), -2) == min(true, -2) == true;

You are warned !
up
2
volch5 at gmail dot com
4 months ago
min() (and max()) 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
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1
dave at dtracorp dot com
8 years ago
empty strings '' will also return false or 0, so if you have something like

$test = array('', 1, 5, 8, 44, 22);

'' will be returned as the lowest value

if you only want to get the lowest number, you'll have to resort to the old fashioned loop

// default minimum value
$minVal = 100;
foreach ($test as $value) {
if (is_numeric($value) && $value < $minVal) {
$minVal = $value;
}
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0
hava82 at gmail dot com
3 years ago
Here is function can find min by array key

<?php
function min_by_key($arr, $key){
   
$min = array();
    foreach (
$arr as $val) {
        if (!isset(
$val[$key]) and is_array($val)) {
           
$min2 = min_by_key($val, $key);
           
$min[$min2] = 1;
        } elseif (!isset(
$val[$key]) and !is_array($val)) {
            return
false;
        } elseif (isset(
$val[$key])) {
           
$min[$val[$key]] = 1;
        }
    }
    return
min( array_keys($min) );
}
?>
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0
matt at borjawebs dot com
3 years ago
A condensed version (and possible application) of returning an array of array keys containing the same minimum value:

<?php
// data
$min_keys = array();
$player_score_totals = array(
'player1' => 300,
'player2' => 301,
'player3' => 302,
'player4' => 301,
...
);

// search for array keys with min() value
foreach($player_score_totals as $playerid => $score)
    if(
$score == min($player_score_totals)) array_push($min_keys, $playerid);

print_r($min_keys);
?>
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0
piotr_sobolewski at o2 dot nospampleasenono dot pl
6 years ago
Be very careful when your array contains both strings and numbers. This code works strange (even though explainable) way:
var_dump(max('25.1.1', '222', '99'));
var_dump(max('2.1.1', '222', '99'));
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0
steffen at morkland dot com
8 years ago
> NEVER EVER use this function with boolean variables !!!
> Or you'll get something like this: min(true, 1, -2) == true;

> Just because of:
> min(true, 1, -2) == min(min(true,1), -2) == min(true, -2) == true;

It is possible to use it with booleans, there is is just one thing, which you need to keep in mind, when evaluating using the non strict comparison (==) anyting that is not bool false, 0 or NULL is consideret true eg.:
(5 == true) = true;
(0 == true) = false;
true is also actually anything else then 0, false and null. However when true is converted to a string or interger true == 1, therefore when sorting true = 1. But if true is the maximum number bool true is returned. so to be sure, if you only want to match if true is the max number remember to use the strict comparison operater ===
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-1
Err
4 years ago
When using a variable with an array that has a list of numbers, put just the variable in min(). Don't use integer index's. Seems pretty straight forward now, but I wasn't used to just putting down the variable for an array in functions.

<?php
  $list
= array(9,5,4,6,2,7);
  echo
min($list); // display 2
?>
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-2
browne at bee why you dot ee dee you
10 years ago
min() can be used to cap values at a specific value. For instance, if you're grading papers and someone has some extra credit, but  that shouldn't make it to the final score:

$pts_possible = 50;
$score = 55;

// Percent will equal 1 if $score/$pts_possible is greater than 1
$percent = min($score/$pts_possible,1);
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