PHP regex and repeated patterns

Question

I'd like to match these strings using preg_match, basicaly only repeated patterns of digits and a comma (optional), no letters

123
123,
123,456
123,456,
123,456,789
123,456,789,
etc...

but not

abc
123,abc
123,abc,456
abc,123,456

thanks

Answer 1

Put comma and the pattern to match one or more digits inside a non-capturing group and then make it to repaet zero or more times. And also don't forget to add an optional comma at the last.

^[0-9]+(?:,[0-9]+)*,?$

DEMO