Get src value containing a specific keyword from all <img> tags

Question

I'm trying to match src="URL" tags like the following:

src="http://3.bp.blogspot.com/-ulEY6FtwbtU/Twye18FlT4I/AAAAAAAAAEE/CHuAAgfQU2Q/s320/DSC_0045.JPG"

Basically, anything that has somre sort of bp.blogspot URL inside of the src attribute. I have the following, but it's only partially working:

preg_match('/src=\"(.*)blogspot(.*)\"/', $content, $matches);

Answer 1

This one accepts all blogspot urls and allows escaped quotes:

src="((?:[^"]|(?:(?<!\\)(?:\\\\)*\\"))+\bblogspot\.com/(?:[^"]|(?:(?<!\\)(?:\\\\)*\\"))+)"

The URL gets captured to match group 1.

You will need to escape \ and / with an additional \ (for each occurence!) to use in preg_match(…).

Explanation:

src=" # needle 1
( # start of capture group
    (?: # start of anonymous group
        [^"] # non-quote chars
        | # or:
        (?:(?<!\\)(?:\\\\)*\\") # escaped chars
    )+ # end of anonymous group
    \b # start of word (word boundary)
    blogspot\.com/ # needle 2
    (?: # start of anonymous group
        [^"] # non-quote chars
        | # or:
        (?:(?<!\\)(?:\\\\)*\\") # escaped chars
    )+ # end of anonymous group
    ) # end of capture group
" # needle 3