RegEx bug?

Question

While I was coding a brainfuck interpreter, I wanted to use RegEx. I wanted to use the re.sub() function to remove a substring from the full code. What I did:
x = re.sub(substr, "", x, 1)
Values at this point (with a sample code) are:
substr = "[#>#+#+#+#+#+#+#+#<#-#]"
x = "+#+#+#+#+#+#+#+#+#[#>#+#+#+#+#+#+#+#<#-#]#>#-#.#+#"
I use the # character for debugging

What happens: instead of replacing the occurence of substr in x with "", it does it to the very first symbol of x. Why? What else could I do?

Answer 1

actually, I just got an idea for it, but its too late now, gonna try it tomorrow

Answer 2

My sample program was one that generated the ascii char 'E', and trust me, that was the best E I ever saw

Answer 3

Lemme try

Answer 4

I can leave my code here if you want

Answer 5

I coded in an external app, ill put it here as private

Answer 6

https://code.sololearn.com/cFNXvHsW1xUK/?ref=app

Answer 7

I already inserted the backslashes to solve the RegEx problem, but it still doesnt work. I know why, and im pretty sure it cant be fixed...

Answer 8

the replacing works perfectly, but theres another seperate bug that cant be fixed...

Answer 9

I DID IT!
https://code.sololearn.com/cPdLTp5l2w7O/?ref=app

Answer 10

I'd have to see the code to help you. But off the top of my head - maybe try preceeding the strings with r to mark them as raw, maybe it helps.

Answer 11

Actually I will update, I managed to get it all into the function

Answer 12

@Kuba how do you... rawify an unknown string?

Answer 13

nope doesnt work, anyways I gave up on this, now trying it in ruby

Answer 14

I tested it with some other programs and made some improvements, not gonna add them here though because they involve the executing, not just the converting

Answer 15

Got it, man. In your code the substr is a string which contains regex-wise special characters. Unfortunately it seems like *each* of them has to be escaped. If you use the following, it will be found and replaced with what you want:

substr = r"\[#>#\+#\+#\+#\+#\+#\+#\+#<#\-#\]"

Answer 16

No way, man! I'll get to it in the evening... 🐍
Check back tomorrow, if you will ;)

Answer 17

Yep, pls publish it on your code list or let me know the link to it, if private.

Answer 18

Weird, works for me :)
I tried with different char strings and it only worked after all special elements were escaped. You got another solution?

Answer 19

Amazing! I just tried it with the Hello World and it worked perfectly 👏

Answer 20

code = "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>."