正则表达式匹配一个网址并替换为另一个网址

Question

Helo,

I am a regular expression noob, trying to find resources online but the language is so foreign to me. Appreciate if anyone can help to shed some light on this.

Basically, I have successfully able to use dom method to find an image url in "img" tag using getAttribute('src') in a random string.

Example:

$string = '<a><img src=http://123.com/123.jpg/></a><img src=http://test.com/test.jpg/>'; //some random string
$url = get_img_url($string) //function of getting a url from a string.

Now here comes the challenge. How do I replace $url with another url, say, $url2? And subsequently save to $newstring? I have thought of using preg_replace, but how do I go about having this?

$url2 = 'http://example.com/content_image/blogger_1.jpg';
$find = ???                 //find $url i gotten in the function above in $string
$replace = ???              //replace with $url2
$newstring = preg_replace($find, $replace, $string);

Any help would be appreciated! Thanks guys!

Edited: Appended desired output, thanks Amit Joki!

echo $newstring;

Result would be:

<a><img src=http://example.com/content_image/blogger_1.jpg/></a><img src=http://test.com/test.jpg/>

Answer 1

You can use this regex:

(<img.+?src=)(.+?)(\s|>)

and replace it with:

$1http://example.com$3

Demo

I don't know php, but you've to do it as:

preg_replace($pattern, $replacement, $string);

where $pattern is my regex, $replacement is my replace string and $string is your inputstring.