php tagging, remove multiple spaces

Question

I have the following code

//check out the tags, if it allready exist update with 1 if not create new record
        $tag_item = "";
        $tags = explode(" ", $tags);
        foreach($tags as $tag):
            if(!empty($tag) && $tag != " "):
                $t_sql = mysqli_query($link, "SELECT id, times FROM shop_tags WHERE tag='".$tag."'");
                if(mysqli_num_rows($t_sql) == 0):
                    mysqli_query($link, "INSERT INTO shop_tags (tag, times) VALUES ('".$tag."', 1)");
                    //find last updated id of the tags
                    $lastid = mysqli_insert_id($link);
                    $tag_item .= $lastid." ";
                endif;
            endif;
        endforeach;

So I use explode to seperate each tag, but what if a user by accident added to spaces? should I use preg_match first to filter for this? and how do I remove the last white space if there is any?

Answer 1

To remove white spaces, the first though is to use trim(), which you could either do in the loop for each tag

foreach($tags as $tag):
    $tag = trim($tag);

or before:

$tags = explode(" ", $tags);
$tags = array_map('trim', $tags);

In both cases, you will end up having to filter out the empty items in $tags

foreach($tags as $tag):
    $tag = trim($tag); //This line is only required if you didn't use array_map
    if ( empty($tag){
        continue;
    }

So it would possibly just be better to use preg_replace

$tags = preg_replace('/\s\s+/',' ', $tags);
$tags = explode(' ', $tags);

Which would ensure that multiple white spaces are converted into a single space before exploding.

Answer 2

You could search for (\s)+ and replace it with a single space. Then trim your string to take care of any trailing white-space.

Answer 3

$tags = explode(" ", $tags);

This'll explode spaces into their own tags. Filter yourself with the foreach, which you do. Modify that if...

if(!empty(trim($tag))):

You could also trim ahead of time.

array_filter($tags, "trim");

Personally, I use commas to delimit tags to allow for tags that have spaces.

Answer 4

First remove possible one or more empty spaces:

$tags = preg_replace('/\s\s+/',' ', $tags);

Remove ending space if there is one:

$tags = ltrim($tags);

And then you explode and proceed further:

$tags = explode(' ', $tags);

Answer 5

You could use the preg functions - but the str_replace function is a lot faster in this case. Also, regarless of which approach you take, you need to apply the method TWICE - in case there are an odd number of consecutive spaces (greater than 1):

$tags=str_replace('  ',' ',trim($tags)); // replace 2 spaces with 1
$tags=str_replace('  ',' ',$tags); // again
$tags=explode(' ', $tags);

C.