Is it possible to screen characters well with a regular expression sieve? Lets firmly fix the description of the regular expression that you often use in your memory with a quiz that makes the regular expression look like a "mesh of a sieve". There are 74 questions in total. From basic level simple problems to deliberately twisted problems. You can solve it while organizing your knowledge in order from 1, and if you are confident, there is also a menu where you can ask 10 questions at random. For those who are interested in regular expressions but are still studying, or who feel that they still do not understand, we also introduce means to learn from the basics. Please feel free to use regular expressions with this app.