Count negative values in a PHP array

Question

I have an array which looks something like this:

array(-2, -1, 0, 1, 2, 3, 4)

I would like to count the number of negative numbers only. I can't spot where it says how to do this in the manual, is there no function to do this? Do I have to create a loop to go through the array manually?

Yes, there's no count_negative_numbers_in_array function build in. You'll have to do it yourself. — deceze
– deceze ♦, Commented Feb 13, 2013 at 13:34
And now, seriously. Why do people try to overcomplicate things by calling several built-in functions? Just because that they have golden name "built-in"? — Leri
– Leri, Commented Feb 13, 2013 at 13:39
@PLB Sure, combining several built-in methods will of course solve the problem... :P — deceze
– deceze ♦, Commented Feb 13, 2013 at 13:48
@deceze I was just kidding. ;) btw, people should be missing something like this (especially if they come from .net). — Leri
– Leri, Commented Feb 13, 2013 at 13:56

sh03 · Accepted Answer · 2013-02-13 13:40:19Z

3

Do I have to create a loop to go through the array manually?

Yes, you have to do it manually by easily doing:

function count_negatives(array $array) {
    $i = 0;
    foreach ($array as $x)
        if ($x < 0) $i++;
    return $i;
}

At the end of the script $i will contain the number of negative numbers.

edited Feb 13, 2013 at 13:40

answered Feb 13, 2013 at 13:34

sh03

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2 Comments

dognose Over a year ago

The Op knows that, he asked for build in functionality. So answer is there is None.

Patrick Guinness Over a year ago

Thanks for the quick answer, and saves me a bit of typing too :) Nice. Thank you Jeffery

adriaan · Accepted Answer · 2013-02-13 13:38:35Z

1

I should use this:

$array = array(-2, -1, 0, 1, 2, 3, 4);

function negative($int) {
     return ($int < 0);
}

var_dump(count(array_filter($array, "negative")));

answered Feb 13, 2013 at 13:38

adriaan

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1 Comment

JMax Over a year ago

i find this solution more elegant and still readable (event with the use a lambda function inside the array_filter)

Adem Öztaş · Accepted Answer · 2013-02-14 04:10:03Z

1

You can use array_filter

function neg($var){
    if($var < 0){
        return $var;
    }        
}

$array1 = array(-2, -1, 0, 1, 2, 3, 4);
print count(array_filter($array1, "neg"));

edited Feb 14, 2013 at 4:10

answered Feb 13, 2013 at 13:40

Adem Öztaş

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Comments

Christoph Grimmer · Accepted Answer · 2013-02-13 13:37:09Z

0

Use array_filter http://www.php.net/manual/en/function.array-filter.php

function isnegative($value){
    return is_numeric($value) && $value < 0;
}

$arr = array_filter(array(-1,2,3,-4), 'isnegative');

echo length($arr);

Have fun.

answered Feb 13, 2013 at 13:37

Christoph Grimmer

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Comments

Christian Kiewiet · Accepted Answer · 2013-02-13 14:39:15Z

0

Try this:

$aValues = array(1, 2, 3, -1, -2, -3, 0);
echo sizeof(array_filter($aValues, create_function('$v', 'return $v < 0;')));

answered Feb 13, 2013 at 14:39

Christian Kiewiet

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