I'm trying to write a regex in Go to test for Latin letters only.
I know that \p{Latin} matches with any Latin script characters, but it also matches things such as Roman Numerals (e.g. "ⅻ").
That leads me to \p{L} which matches Unicode letters, but it matches any script, not just Latin.
Best I've been able to come with so far is two regexes with an &&:
latinRe := regexp.MustCompile(`\p{Latin}`)
letterRe := regexp.MustCompile(`\p{L}`)
if latinRe.Matches(testString) && letterRe.Matches(testString) {...}
I'm not happy that I can't test this as easily using something like regex101.com.
Is there a better way? More succinct? Performant?
You can use a range like the following to specify all the characters you want to match. Depending on the regex engine, one of the following should work:
See regex in use here: Adapted from this link
[A-Za-z\u00C0-\u00D6\u00D8-\u00f6\u00f8-\u00ff]
[A-Za-z\xC0-\xD6\xD8-\xf6\xf8-\xff]
Another option is to negate specific characters from a Unicode character class:
See regex in use here
[^\P{Latin}\p{N}]
Related
I have a very large file containing thousands of sentences. In all of them, the first word of each sentence begins with lowercase, but I need them to begin with uppercase.
I looked through the site trying to find a regex to do this but I was unable to. I learned a lot about regex in the process, which is always a plus for my job, but I was unable to find specifically what I am looking for.
I tried to find a way of compiling the code from several answers, including the following:
Convert first lowercase to uppercase and uppercase to lowercase (regex?)
how to change first two uppercase character to lowercase character on each line in vim
Regex, two uppercase characters in a string
Convert a char to upper case using regular expressions (EditPad Pro)
But for different reasons none of them served my purpose.
I am working with a translation-specific application which accepts regex.
Do you think this is possible at all? It would save me hours of tedious work.
You can use this regex to search for the first letters of sentences:
(?<=[\.!?]\s)([a-z])
It matches a lowercase letter [a-z], following the end of a previous sentence (which might end with one of the following: [\.!?]) and a space character \s.
Then make a substitution with \U$1.
It doesn't work only for the very first sentence. I intentionally kept the regex simple, because it's easy to capitalize the very first letter manually.
Working example: https://regex101.com/r/hqwK26/1
UPD: If your software doesn't support \U, you might want to copy your text to Notepad++ and make a replacement there. The \U is fully supported, just checked.
UPD2: According to the comments, the task is slightly different, and just the first letters of each line should be capitalized.
There is a simple regex for that: ^([a-z]), with the same substitution pattern.
Here is a working example: https://regex101.com/r/hqwK26/2
Taking Ildar's answer and combining both of his patterns should work with no compromises.
(?<=[\.!?]\s)([a-z])|^([a-z])
This is basically saying, if first pattern OR second pattern. But because you're now technically extracting 2 groups instead of one, you'll have to refer to group 2 as $2. Which should be fine because only one of the patterns should be matched.
So your substitution pattern would then be as follows...
\U$1$2
Here's a working example, again based on Ildar's answer...
https://regex101.com/r/hqwK26/13
I am looking through volumes of data and need to identify certain patterns one of which is abbreviations. The basic rules to identify them in the content I am going through is
They are all is capital letters.
They are separated by dots.
They may be one or more alphabets
They may or may not end with a dot.
I am looking at individual words therefore looking for multiple occurrences in the string is not required.
Examples
U.S., U.S, U.S.S.R., V.
Can someone help construct a regex search pattern for me?
Many thanks
MS
You can use this regex:
^([A-Z]\.)*[A-Z]\.?$
RegEx Demo
This should do the trick:
\b(?:\p{Lu}\.)*\p{Lu}\b\.?
Demo
I've used \p{Lu} (unicode uppercase letters) since you want to match any alphabet.
If you can't make \b unicode aware in your dialect, here's an alternative:
(?<!\p{L})(?:\p{Lu}\.)*\p{Lu}(?!\p{L})\.?
This will work. it also matches the ending dots.
\b([A-Z]\.)*[A-Z]\b\.?
I need a regex for allowing list of special characters((_-.$#?,:'/!) and letters supporting utf-8 languages.
I tried
/^[\_\-\.\$#\?\,\:\'\/\!]*$/
but typing letters in English and Tamil shows invalid.
You need to escape the hyphen for it to be valid. You also don't need to escape most of the other characters - inside of brackets, almost everything is literal.
/[_\-.$#?,:'/!]*/
I have no idea if your regex engine supports \p{L}. You can try this:
^[_\-.\$#\?\,\:\'/!\p{L}]*$
or this one:
^[_\-.\$#\?\,\:\'/!\w]*$
The last one also matches digits.
I am trying to form a regular expression that will match strings that do NOT end a with a DOT FOLLOWED BY NUMBER.
eg.
abcd1
abcdf12
abcdf124
abcd1.0
abcd1.134
abcdf12.13
abcdf124.2
abcdf124.21
I want to match first three.
I tried modifying this post but it didn't work for me as the number may have variable length.
Can someone help?
You can use something like this:
^((?!\.[\d]+)[\w.])+$
It anchors at the start and end of a line. It basically says:
Anchor at the start of the line
DO NOT match the pattern .NUMBERS
Take every letter, digit, etc, unless we hit the pattern above
Anchor at the end of the line
So, this pattern matches this (no dot then number):
This.Is.Your.Pattern or This.Is.Your.Pattern2012
However it won't match this (dot before the number):
This.Is.Your.Pattern.2012
EDIT: In response to Wiseguy's comment, you can use this:
^((?!\.[\d]+$)[\w.])+$ - which provides an anchor after the number. Therefore, it must be a dot, then only a number at the end... not that you specified that in your question..
If you can relax your restrictions a bit, you may try using this (extended) regular expression:
^[^.]*.?[^0-9]*$
You may omit anchoring metasymbols ^ and $ if you're using function/tool that matches against whole string.
Explanation: This regex allows any symbols except dot until (optional) dot is found, after which all non-numerical symbols are allowed. It won't work for numbers in improper format, like in string: abcd1...3 or abcd1.fdfd2. It also won't work correctly for some string with multiple dots, like abcd.ab123cd.a (the problem description is a bit ambigous).
Philosophical explanation: When using regular expressions, often you don't need to do exactly what your task seems to be, etc. So even simple regex will do the job. An abstract example: you have a file with lines are either numbers, or some complicated names(without digits), and say, you want to filter out all numbers, then simple filtering by [^0-9] - grep '^[0-9]' will do the job.
But if your task is more complex and requires validation of format and doing other fancy stuff on data, why not use a simple script(say, in awk, python, perl or other language)? Or a short "hand-written" function, if you're implementing stand-alone application. Regexes are cool, but they are often not the right tool to use.
I would just use a simple negative look-behind anchored at the end:
.*(?<!\\.\\d+)$
I need a regular expression to allow the user to enter an alphanumeric string that starts with a letter (not a digit).
This should work in any of the Regular Expression (RE) engines. There is a nicer syntax in the PCRE world but I prefer mine to be able to run anywhere:
^[A-Za-z][A-Za-z0-9]*$
Basically, the first character must be alpha, followed by zero or more alpha-numerics. The start and end tags are there to ensure that the whole line is matched. Without those, you may match the AB12 of the "###AB12!!!" string.
Full explanation:
^ start tag.
[A-Za-z] any one of the upper/lower case letters.
[A-Za-z0-9] any one of the upper/lower case letters or digits,
* repeated zero or more times.
$ end tag
Update:
As Richard Szalay rightly points out, this is ASCII only (or, more correctly, any encoding scheme where the A-Z, a-z and 0-9 groups are contiguous) and only for the "English" letters.
If you want true internationalized REs (only you know whether that is a requirement), you'll need to use one of the more appropriate RE engines, such as the PCRE mentioned above, and ensure it's compiled for Unicode mode. Then you can use "characters" such as \p{L} and \p{N} for letters and numerics respectively. I think the RE in that case would be:
^\p{L}[\pL\pN]*$
but I'm not certain. I've never used REs for our internationalized software. See here for more than you ever wanted to know about PCRE.
I think this should do the work:
^[A-Za-z][A-Za-z0-9]*$
You're looking for a pattern like this:
^[a-zA-Z][a-zA-Z0-9]*$
That one requires one letter and any number of letters/numbers after that. You may want to adjust the allowed lengths.