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(PHP 4, PHP 5)
min — Minimalwert bestimmen
Ist der erste und einzige Parameter ist ein Array, gibt min() den niedrigsten Wert dieses Arrays zurück. Sind mindestens zwei Parameter übergeben, gibt min() den kleinsten dieser Werte zurück.
Hinweis:
PHP evaluiert nicht-numerische string-Daten zu 0, wenn sie mit einem integer-Wert verglichen werden, gibt aber trotzdem die Zeichenkette zurück, wenn sie den numerisch niedrigsten Wert hat. Werden mehrere Argumente zu 0 evaluiert, gibt min() den niedrigstwertigen alphanumerischen String zurück, wenn mehrere Zeichenketten übergeben wurden, andernfalls den numerischen Wert 0.
Ein die Werte enthaltendes Array.
min() liefert den numerisch kleinsten Parameterwert zurück.
Beispiel #1 Verwendungsbeispiel von min()
<?php
echo min(2, 3, 1, 6, 7); // 1
echo min(array(2, 4, 5)); // 2
echo min(0, 'hello'); // 0
echo min('hello', 0); // hello
echo min('hello', -1); // -1
// Bei multiplen Arrays vergleicht min von links nach rechts,
// daher ist in unserem Beispiel 2 == 2, aber 4 < 5
$val = min(array(2, 4, 8), array(2, 5, 1)); // array(2, 4, 8)
// Sind ein Array und ein Nicht-Array-Parameter gegeben, wird
// das Array niemals zurückgegeben, da es als größer betrachtet wird
$val = min('string', array(2, 5, 7), 42); // string
?>
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
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);
?>
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
?>
min/max works with yyyy-mm-dd dates, e.g.
<?php
$a = array( '2008-10-01', '2008-12-01' );
print min($a); // '2008-10-01'
print max($a); // '2008-12-01'
?>
Which is a unexpected since at the top of this page it says.
"PHP will evaluate a non-numeric string as 0"
And if we cast it as an int then we get the year
<?php
print (int)"2008-01-12"; // 2008
?>
I have found a very useful trick to help get round the problem of setting a variable to max int when finding a min i.e.
<?php
$val = 10;
$min = 100000; // This is unpleasant and I couldn't find a equivalent to the C++ MAXINT
if ($val < $min)
{
$min = $val;
}
?>
try this ...
<?php
$dataSet = Array(7, 8, 9, -1, -100, 0, 1, 2, 3, 5, 6);
$min = true;
$max = true;
foreach ($dataSet as $data )
{
echo("data = $data");
$min = min($data, $min);
$max = max($data, $max);
}
echo("min = $min");
echo("max = $max");
?>
$max can be set to anything e.g. "infinity", but the same trick doesn't work with min, however true does work (false doesn't). Not sure why though.
The above code even works with a data set like this...
<?php $dataSet = Array("0.5", 1, 2, "3", "-1", "5"); ?>
but min doesn't like null or negative float e.g. "-1.2" and "" can give some odd results too.
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 $min;
}
?>
A way to bound a integer between two values is:
function bound($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
You will get an "Wrong parameter count" error (PHP 4 and possibly 5) if your array looks like the following:
min(115.23,432.11,0.00,45.76)
The 0.00 creates the error. Convert the 0.00 to a high number such as 10000000000.00 or remove it from the array before running the min() function.
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'));
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;
}
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
> 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 ===
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 !
Here is my slightly modified version of the bugfree min-version. Now the max() function is no longer used in the modification and overall it's fasten up. Would be nice to get some feedback.
<?php
function min_mod () {
$args = func_get_args();
if (!count($args)) return false;
else {
$min = false;
foreach ($args AS $value) {
$curval = floatval($value);
if ($curval < $min || $min === false) $min = $curval;
}
}
return $min;
}
?>
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
?>
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.
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/$pts_possible,1);
Further modifications to the minnum function above.. This is for a project where I had to grab an entire column out of a database consisting of values that might be string, might be string representations of numbers (floating point or integer) or might be NULL, and find the minimum NUMERIC value:
function minnum($numarray){
//dont use min(), it contains a bug!
$min=0;
if ( ! is_array($numarray) ) $numarray = func_get_args();
if(is_array($numarray)==true){
$min=max($numarray);
for($z=0;$z<count($numarray);$z++){
$curval=floatval($numarray[$z]);
if(($curval != 0) && ($curval < $min)){
$min=$curval;
}
}
}
return $min;
}
Gets the floating point value of each entry and uses this to check whether it's actually a number before checking whether it's the minimum or not. Also contains modifications noted above to use it as a drop in replacement for min - ie multiple values passed.
Caution : it seems that min() can return a string :
min(";",50)=";" (I expected zero)
if you have an array like this
$arSrc[0]=14;
$arSrc[1]=16;
$arSrc[2]=13;
$arSrc[3]=17;
then in order to get the min element and its position in the array you can do:
$iMinValue = min($arSrc);
$arFlip = array_flip($arSrc);
$iMinPosition = $arFlip[$iMinValue];
echo
'<br />min_value=',
$iMinValue,
'<br />min_position=',
$iMinPosition
;
this example works for also for an associative array; of course with numeric values
Re: above example - for a proper drop in replacement for the above, insert
if ( ! is_array($numarray) )
$numarray = func_get_args();
after
$min=0;
(For PHP3, check
if (intval(PHP_VERSION) >= 4 && ! is_array($numarray))
$numarray = func_get_args();
)
The 'undefined' behaviour can bit you badly. I would expect min(undefined, -1000) to return -1000. Not so.
If one of elements is undefided, min() result is underfinded too
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