Regex comparison
regex
Solution
The first one requires that there be at least one non-= character before an = in order to match, whereas the second doesn't; it'll match on a leading ==.
Depending on your content, the first one could run significantly faster. Here's why:
An Alternative to Laziness In this case, there is a better option than making the plus lazy. We can use a greedy plus and a negated character class: <[^=]+>. The reason why this is better is because of the backtracking. When using the lazy plus, the engine has to backtrack for each character in the HTML tag that it is trying to match. When using the negated character class, no backtracking occurs at all when the string contains valid HTML code. Backtracking slows down the regex engine. You will not notice the difference when doing a single search in a text editor. But you will save plenty of CPU cycles when using such a regex repeatedly in a tight loop in a script that you are writing...
Problem
I'm (finally) starting to learn regex, and I'm wondering if there's any notable difference between these two pattern strings. I'm trying to match lines such as "`Title=Blah`", and match "Title" and "Blah" in two groups. The problem comes with titles like "`Title=The = operator`". Here are the two choices to solve the problem: ``` ^([^=]+)=(.+)$ ^(.+?)=(.+)$ ``` Is there any difference between the two, either performance-wise or functionality-wise?