When I replace spaces, dots and commas of a string, it sometimes happens that I get double hyphens.

For example turns check out the 1. place into check-out-the-1--place

How can I avoid that? I want it to be check-out-the-1-place - so that there only is one hyphen between each word. Here is my code:

str_replace([' ', ',', '.','?'], '-', strtolower($pathname));

Right now, I know why it returns the double-hyphens, but I don't know how to work around that.

Can someone help me out?

How can I avoid that? I want it to be check-out-the-1-place - so that there only is one hyphen between each word. Here is my code:

Whilst Mohammad's answer is nearly there, here is a more fully working PCRE regex method and explanation as to how it works, so you can use it as you need:

$str = trim(strtolower($pathname));
$newStr = preg_replace('/[\s.,-]+/', '-', $str);

How this works:

• Match a single character present in the list below [\s.,-]+
  • + Quantifier Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)
  • \s matches any whitespace character (equal to [\t\f\v])
  • .,- matches a single character in the list .,- (case sensitive)
  • The dash - must come at the end of the [] set.

Results:

This: check out the 1. place

Becomes:

check-out-the-1-place

And

This: check out the - 1. place

Becomes

check-out-the-1-place

Further:

I would go further and assuming you are using this for a URL slug (a what?!); strip out all non-alphanumeric characters from the string and replace with a single - as per typical website slugs.

 $newStr = preg_replace('/[^a-z0-9]+/i', '-', $str);

How this works:

• Match a single character NOT (^) present in the list below [a-z0-9]+
  • + Quantifier Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)
  • a-z a single character in the range between a (index 97) and z (index 122) (case sensitive)
  • 0-9 a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
  • The i at the end indicates the judgements are case In-sensitive.

Example:

check out - the no.! 1. Place

Becomes:

check-out-the-1-Place

You can use preg_replace() instead and user regex to selecting multiple specific character.

$newStr = preg_replace("/[\s.,]+/", "-", $str)

Check result in demo