Surprising regular expression !

guy038

Hi, All,

Here is a little exercise for a Sunday !

Start N++ and open a new file ( Ctrl + N )
Write 2,047 consecutive empty lines
Save your file
Move back to its very beginning ( Ctrl + Home )
Select the Edit > Column Editor.. option or use the Alt + C shortcut
Enter the values 0 , 1 , 1 to define the sequence
Select the leading Zeros option and the Bin format

=> You should get a list of binary numbers between 0 and 111 1111 1111

Now, open the Mark dialog ( Ctrl + M )
- Uncheck all box options
- Enter the regex ^(0|(1(01*0)*1))*$ in the Find what field
- Check the Bookmark line and Wrap around options
- Select the Regular expression mode
- Click on the Mark All button
Close the Mark dialog or hit the ESC key

Now, in your opinion, what do all these marked lines represent ? …

After a while, it should be enough easy to detect that any marked line is a number multiple of 3 !

Therefore, the main takeaway from this text, is that regexes can simulate mathematical formulas !

Of course, I did not come up with that regex on my own, but by referring to the last example in this Wikipedia article :

https://en.wikipedia.org/wiki/Regular_expression#Formal_definition

Now, I suppose that other regexes could simulate other multiples or formulas, as long, as we simply use the binary format but I have not tested anything yet !

Best Regards,

guy038