PHP shortest/longest string length in array

Question

I have an array like this

$data = array(
    "163",
    "630",
    "43",
    "924",
    "4",
    "54"
);

How can I select the smallest and largest values from it according to string length NOT number value. (for this example it is 1 (smallest) and 3 (largest).

Solution 1

Seems like you should use an array_map()

  // Convert array to an array of string lengths
$lengths = array_map('strlen', $data);

  // Show min and max string length
echo "The shortest is " . min($lengths) .
     ". The longest is " . max($lengths);

Note that the $lengths array is unsorted, so you can easily retrieve the corresponding number for each string length.

Solution 2

Here's an improved version of brian_d's code:

$min = PHP_INT_MAX;
$max = -1;

foreach ($data as $a) {
    $length = strlen($a);
    $max = max($max, $length);
    $min = min($min, $length);
}

Solution 3

Although in this case it is not advisable because you'll be traversing the array twice, you can also use array_reduce to compare each element against the rest. Like this:

<?php

$data = array('163','630','43','42','999','31');
//Will return the longest element that is nearest to the end of the array (999)
//That's why we use strlen() on the result.
$max_l = strlen(array_reduce($data,'maxlen'));
//Will return the shortest element that is nearest to the end of the array (31)
$min_l = strlen(array_reduce($data,'minlen'));

echo "The longest word is $max_l characters, while the shortest is $min_l\n";

function maxlen($k,$v) {
        if (strlen($k) > strlen($v)) return $k;
        return $v;
}
function minlen($k,$v) {
        if ($k == '') return PHP_INT_MAX;
        if (strlen($k) < strlen($v)) return $k;
        return $v;
}
?>

If you are using PHP 5.3.0+ you can take advantage of closures:

<?php
   $max_l = strlen(array_reduce($data,
                function ($k,$v) { return (strlen($k) > strlen($v)) ? $k : $v; }
        ));

   $min_l = strlen(array_reduce($data,
                function ($k,$v) {
                        if (!$k) return PHP_INT_MAX;
                        return (strlen($k) < strlen($v)) ? $k : $v;
                }
        ));

echo "The longest word is $max_l characters, while the shortest is $min_l\n";
?>

Solution 4

$min = 100;
$max = -1;

foreach($data as $a){
  $length = strlen($a);
  if($length > $max){ $max = $length; }
  else if($length < $min){ $min = $length; }
}

Solution 5

<?php
$array = array(
    "163",
    "630",
    "43",
    "924",
    "4",
    "54"
);
$arraycopy  = array_map('strlen',$array);
asort($arraycopy);

$min = reset($arraycopy);

//if you need a single 'minword'
$minword = $array[key($arraycopy)];
//if you need them all
$minwords = array_intersect_key($array,array_flip(array_keys($arraycopy,$min)));


$max = end($arraycopy);
//if you need a single 'maxword'
$maxword = $array[key($arraycopy)];
//if you need them all:
$maxwords = array_intersect_key($array,array_flip(array_keys($arraycopy,$max)));

var_dump($min,$max,$minword,$maxword,$minwords,$maxwords);

View more solutions

Comments

[Femaref]

it does exactly what the op wants.

[Femaref]

that's right though. $min has to start at a very high number (int32.maxvalue perhaps?)

[Matthew]

Or you can set $max/$min to the first element and (optionally) skip it in the iteration. (Easier to do that with a for loop.)

[NullUserException]

@konforce: With that approach you'd have to make sure you are accessing valid entries (think of arrays with 0 or 1 elements), and will introduce more checks.

[Matthew]

Either way you have to check for an empty array. With Brian's code, you get $min=100, $max = -1 on an empty array. So assuming you now have a non-empty array, there is no additional condition with for ($i = 1; $i < $len; ++$i). And in fact, you avoid the if/else on the first iteration (since it's skipped). Plus, foreach tends to be the worst performing way to iterate in PHP. But these are minor points, and I digress...

[NullUserException]

+1 Neat. You could just do array_map('strlen', $data) though;

[Vinko Vrsalovic]

This is by far the cleanest solution, but it's not very efficient, as it traverses the array three times (array_map, min and max), so if you have huge arrays, better use a single loop.

[Peter Ajtai]

This seems overly complex (with the addition of an initialized $min and $max), unless you are dealing with a huge array that you only want to traverse once.

[Peter Ajtai]

@Vinko - Yeah, I guess that's where NullUserException's answer would gain the advantage (in the case of a huge array... or using this function very very many times on many many arrays).

[mickmackusa]

Yeesh, three function calls on every iteration? I wouldn't.

[mickmackusa]

Mapping the same array twice with strlen to produce the same outcome is the nonsensical way of executing the accepted answer (posted 9 years earlier). No new value in this post.

[mikep]

Be careful of strlen - it is string length in bytes not count of chars. Count of chars is bigger in case of special (multibyte) chars so mb_strlen must be used.