Yesterday, I talked about how to get the most out of running regular expressions in PHP. The reason that I needed to dig in deep on regular expression syntax with PHP is because I needed to write some regular expressions that deal with Unicode characters.
After much reading, I believed that I knew everything that I needed. I started writing some regex strings and testing the code. Unfortunately, every time I ran a test with a string that contained Unicode characters, the match failed. When I removed the Unicode characters from the string and tested again, it would work. I was baffled.