❔ Match literal escape strings with a regex
Hi everyone,
I'm trying to write a simple regex so that each literal escape hexadecimal character notation is matched.
For example, in the string "hey there \x68" , i'm interested in matching "\x68", and not the unescaped "h" character.
I wrote the following Regex: "\x[0-9a-f]{2}", but it seems that the Regex.Matches method still looks at it like I'm trying to match characters using an escaped notation, as I have the following error: " Invalid pattern '\x[0-9a-f]{2}' at offset 3. Insufficient hexadecimal digits."
Does anyone know how I can specify that I want the literal strings of the form "\xnn" to be matched, rather than the corresponding unescaped characters?
Thanks!
15 Replies
can you paste the code
like what string literal are you using as an argument to Regex
"" or @""
because \ would be escaped
I tried either:
string charASCIICodeRegex = "\\x[0-9a-f]{2}";
var Matches = Regex.Matches(line, charASCIICodeRegex);
and:
string charASCIICodeRegex = @"\x[0-9a-f]{2}";
var Matches = Regex.Matches(line, charASCIICodeRegex);
without successhave you tried
you have two different regex there
it's that one yeah
ero
REPL Result: Success
Result: bool
Compile: 454.167ms | Execution: 30.453ms | React with ❌ to remove this embed.
as
\ has an escape meaning in regex itself u need to escape that as well. so to match a backslash u need to use @"\\" or "\\\\"
but u already have an issue here: what if the content is @"\\x1", it would match on the @"\x1" while its actually being escapedOK Thanks everyone! I just kinda missed one layer of escape meaning. That makes sens!
Whoops, I didn't think about that. It's for a simple AdventOfCode puzzle, so I don't know if I'll stump upon this issue, but that's a good point!
regexes are good for simple patterns but u might need an actual parser here
but it depends on what u want to achieve, u can also just
@"(\\+)x([0-9a-fA-F]{2})" and afterwards check if the first group has an odd length (if yes the last \ isnt escaped) to go furtheri don't understand this at all lol
how would that match when we have
{2}aah, yeah, it doesnt, my focus was on the backslash, not on the hexadecimal number
ah
assume the content was
\\x10 ;p, it would match on the \x10 but the \ is actually escapedYup, I didn't even notice that you put only one hex digit, but I got the idea. Thanks!
note, that depending on context escape hexadecimal notation
\\x10 could still be resolved to backslash + the Was this issue resolved? If so, run
/close - otherwise I will mark this as stale and this post will be archived until there is new activity.