PHP oneliner检查字母数字+ - ，_和

Question

I need simple one liner to check for alphanumeric characters with -, _ and . (for filenames), to be used as an if condition.

I tried several things, including ctype_allnum and preg match, but I can't get it to work. For example:

if(!ctype_alnum(preg_replace("-_\.", "", "should_pas-s.html")))
{ sth; }

I know about ctype_alnum, but that takes external (not in one line) array, so it would complicate things. (There are many conditions to check.)

Answer 1

The issue you have is with the usage of preg_replace. The documentation tells a bit about what the pattern should look like.

You need to put begin and end delimiter in your regular expression. For example:

preg_replace("#-_\.#", "", "should_pas-s.html")

so in your case the code should be:

if(!ctype_alnum(preg_replace("#-_\.#", "", "should_pas-s.html")))

This is already answered in this question: Warning: preg_replace(): No ending delimiter '/' found

Or this one: What Delimiter to use for preg_replace in PHP (replace working outside of PHP but not inside)