Concatenate strings from array in PHP ignoring blanks

Question

Similar to this question but for PHP. I want to concatenate an array of strings but ignore blanks.

For instance, suppose I want to build a full_name attribute in Laravel using $this->title, $this->first_name, and $this->last_name, each separated by single space. The simplest thought I had was to put them all into an array and pass it into implode() as in below:

implode(' ', [$this->title, $this->first_name, $this->last_name]);

However I don't know whether those values are actually going to be set or not. And if they are set, I don't want empty strings to pollute the output with multiple spaces between non-empty elements. Is there a built-in function or at least a simpler/shorter way to do the below?

public function concatenateStringsFromArray($glue = ' ', $arrayOfStrings)
{
    $result = '';
    foreach($arrayOfStrings as $piece)
        $result .= isset($piece) ? $piece . $glue : '';
    return $result;
}

@unclexo i can't see how that would prevent consecutive spaces from appearing due to nulls/blanks in the middle of the array. — Erich
– Erich, Commented Feb 20, 2020 at 4:37
I can't see what your goal is. What should come out of this input array ['a', ' b c',null, ' ','def '] — jspit
– jspit, Commented Feb 20, 2020 at 6:56
@jspit good question -- i was assuming that provided strings would be single words without any whitespace (or at least trimmed). to fail the test, strings should be not null or empty (i.e. ''). so your array should result in a b c def i think. — Erich
– Erich, Commented Feb 20, 2020 at 14:24

jspit · Accepted Answer · 2020-02-20 07:18:49Z

2

array_map with trim as function removes all spaces at the beginning and end of a string, not in the middle. array_filter removes then all elements that are empty, including zero and "".

$arrayOfStrings = ['a', 'b    c',null, '    ','ef ','  012'];

$result = implode(' ', array_filter(array_map('trim',$arrayOfStrings)));

echo '<pre>'.$result;  //a b    c ef 012

I wrote everything on one line because you wanted it to be short.

answered Feb 20, 2020 at 7:18

jspit

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1 Comment

Erich Over a year ago

produces "a b c ef 012". this is a good substitute for unclexo's answer if you need to do clean up first.

unclexo · Accepted Answer · 2020-02-20 16:20:52Z

1

Apply trim() function on each array element. See the following example:

<?php

$arrayOfStrings = ['a', ' b c',null, ' ','def '];

echo implode(' ', array_filter($arrayOfStrings, function($element) { 
    return trim($element); 
}));

The code above outputs "a b c def ". Notice the space after "def ".

This means trim() function with array_filter() function's callback function doesn't trim space from the right side. To address this issue, you should use trim() function with array_filter() and array_map() functions. Because array_map() function removes spaces from both sides. See the following example:

<?php

echo implode(' ', array_filter(array_map('trim', $arrayOfStrings)));

The code above outputs "a b c def"

By the way thanks to @jspit for the good catch!

edited Feb 20, 2020 at 16:20

answered Feb 20, 2020 at 4:55

unclexo

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7 Comments

Erich Over a year ago

that works well! on @jspit's test array above, produces "a b c def ".

jspit Over a year ago

@Erich : The result is not the same. You have to output an echo "<pre>" in advance to see all spaces!

Erich Over a year ago

@jspit your comment on the question i only saw ['a', ' b c',null, ' ','def ']. was there a space in front of the a?

Erich Over a year ago

@jspit i'm not formatting the output for an html canvas, so no need for <pre>

jspit Over a year ago

The '<pre>' only serves to make the spaces visible in the browser. However, the spaces are in the string. Do a var_dump() and also look at the number of characters. I don't know if the difference bothers you.

|

brett · Accepted Answer · 2020-02-20 06:58:12Z

0

array_filter() should do the trick. Simply calling implode($glue,array_filter($array)) should give you what you want, by filtering out all elements of the given array which resolve to false (0, null and '' among others). If you need 0 or other values which resolve to boolean false as valid values you can use a custom callback:

array_filter($array, function($value) { return !is_null($value) && $value !== ''; })

answered Feb 20, 2020 at 6:58

brett

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Comments

Mike Doe · Accepted Answer · 2020-02-20 07:35:33Z

0

Adapted from an example using array_filter:

return implode($glue, array_filter($arrayOfStrings, function($element) { 
    return $element !== null && $element !== ''; 
}));

edited Feb 20, 2020 at 7:35

Mike Doe

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answered Feb 20, 2020 at 4:42

Erich

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