Question

My understanding of regex and working with strings in php is poor at best so my apologies if this is a simple question for most. If I’m honest the searches I have made have confused me more than anything else, hopefully someone here can give me a clear answer.

I simply need to increment the suffix of file names in PHP.

The file names look like the following:

13132432343243432434234_1.jpg

I wish to keep the file name exactly as is, but replace the final ‘_1’ part with ‘_2’, ‘_3’, ‘_4’ etc.

There is no need to check if the file exists, this needs to be a simple string manipulation. If the suffix is _1, then replace it with _2 and if the suffix is _4, then replace it with _5 etc.

Thanks in advance.

Answer 1

Something along these lines should do it:

echo preg_replace_callback('/(?<=_)\d+(?=\.)/',
                           function ($m) { return ++$m[0]; },
                           '13132432343243432434234_1.jpg');

The regex matches “any number preceded by a _ and followed by a .“, the callback returns this number incremented by one.