min function that ignores negative values in php

I have thre开发者_如何学Ce numbers:

$a = 1
$b = 5
$c = 8

I want to find the minimum and I used the PHP min function for that. In this case it will give 1.

But if there is a negative number, like

$a = - 4
$b = 3
$c = 9

now the PHP min() should give $b and not $a, as I just want to compare positive values, which are $b and $c. I want to ignore the negative number.

Is there any way in PHP? I thought I will check if the value is negative or positive and then use min, but I couldn't think of a way how I can pass only the positive values to min().

Or should I just see if it's negative and then make it 0, then do something else?

You should simply filter our the negative values first.

This is done easily if you have all of them in an array, e.g.

$a = - 4;
$b = 3;
$c = 9;

$values = array($a, $b, $c);
$values = array_filter($values, function($v) { return $v >= 0; });
$min = min($values);

print_r($min);

The above example uses an anonymous function so it only works in PHP >= 5.3, but you can do the same in earlier versions with

$values = array_filter($values, create_function('$v', 'return $v >= 0;'));

See it in action.

$INF=0x7FFFFFFF;

min($a>0?$a:$INF,$b>0?$b:$INF,$c>0?$c:$INF) 

or

min(array_filter(array($a,$b,$c),function($x){
    return $x>0;
}));

http://codepad.org/DVgMs7JF

<?
$test = array(-1, 2, 3);

function removeNegative($var)
{
   if ($var > 0)
       return $var;
}

$test2 = array_filter($test, "removeNegative");

var_dump(min($test2));
?>