Is it possible to match the first word in a file using Visual Studio Regex?
e.g. ^using matches multiple statements where "using" matches the first five characters on a line.
I need to find and replace the only first using statement where "using" matches the first five characters in the file.
Thanks,
M
Well, regex matches against a string. So, you could try reading the first line of the file into a string and execute a regex match against that string.
Related
I met the following the regex in ruby code, anyone could detail this to me?
[\w-]+\.(?:doc|txt)$
especially I think I am not clear about [\w-]+\ and ?:
It is a sequence of one or more letter/number/underscore/hyphen, followed by the period, followed by either doc or txt at the end of a line.
[\w-] is letter/number/underscore/hyphen.
\. is an escaped period.
(?:...) is a grouping (required to express options between doc and txt) that would not appear in the result as a captured substring.
It is likely written for searching a file name with the extension doc or txt, embedded within a multi-line string. Or, if the author of that regex is stupid (mistaking $ for \z), then it might have been intended to simply match a file name with that extension.
There is an online regex tester available at https://regex101.com/
You can use it to analyse, verify or debug your regex strings. It already saved me tons of time.
Your regex detailed automatically with the help of that tool:
/[\w-]+\.(?:doc|txt)$/
[\w-]+ match a single character present in the list below
Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
\w match any word character [a-zA-Z0-9_]
- the literal character -
\. matches the character . literally
(?:doc|txt) Non-capturing group
1st Alternative: doc
doc matches the characters doc literally (case sensitive)
2nd Alternative: txt
txt matches the characters txt literally (case sensitive)
$ assert position at end of the string
\w means any word character
minus in this context just means minus char
(?:doc|txt) means match doc or txt
so any word char or a minus repeated one or more times followed by a dot followed by either doc or txt and the pattern must be at the end of the line
the author should have escaped the minus for clarity imho
It means a file name which contains only word characters (a-z, A-Z, 0-9 and underscore) and hyphens, and with an extension of either .doc or .txt.
In detail,
\w matches a word character
[\w-] matches either a word character or a hyphen
[\w-]+ matches one or more such characters
\. matches a period
(?:) forms a non-capture group
(?:doc|txt) matches either a doc sequence, or a txt sequence
In ruby, $ matches the end of a line
My question is how to match the first three characters of certain lines within a string using regular expressions the regex i have should work however when i run the program it only matches the first three characters of the first line the string is
.V/RTEE/EW\n.N/ERER/JAN/21
my regex is ^(.[VN]/)* so it needs to match .V/ and .N/ any help I will be very grateful
You need to suppress the special meaning of the . and /
Use \ in-front of them.
I am trying to replace a specific pattern in a text string.
That pattern is a href containing the word "sak".
My script currently looks like this:
ccontent=ccontent.sub(/<a .+?href=\"([^\"]+)\"[^\>]*>Sak<\/a>/, '')
The problem is that this replaces the entire string. (the string contains two links).
The problem is somewhere around the `a .+?" symbols, it runs through the link i want to Replace entirely and goes into the next link and replaces that whole link as well.
But I want it to STOP when the first pattern match is reached so that it only erases "sak" link.
How do i make the pattern match stop at the first time it reaches the 'href'?
Your expression is greedy, because .+? will actually keep matching any character as long as the pattern still matches.
Just use the [^>]* character set you're already using at the end of the regex:
ccontent.sub(/<a [^>]*href=\"([^\"]+)\"[^>]*>Sak<\/a>/, '')
I need to do a find and replace, where I need to replace 2 lines at time. Does anyone know how to do this in the VS2008 IDE?
To clarify, i want to replace 2 lines with 1 line.
Many thanks
Thanks to František Žiačik for the answer to this one.
To perform a find/replace, replacing multiple lines, you need to switch on regular expressions and use a line break (\n) between your lines, also using (:b*) at the start of each line to handle any tabs or spaces tabs.
So to find:
line one
line two
you would search for ":bline one\n:bline two" (without the quotes)
Try Multiline Search and Replace macro for Visual Studio.
You can activate the 'Use regular expressions' in the find dialog, and use \n to match a newline.
In your case, type FirstLine\n:Zs*SecondLine.
:Zs* skips leading blanks on line 2.
For example ,\n:Zs*c matches a comma, newline, any number of blanks, a 'c'.
Sometimes i would like to search for text containing a new line character and there are other times i would like to replace text with a new line character.
How can i do this with visual studio 2008?
Use a RegEx search:
In the Find Dialog - Expand "Find Options"
Check the box for Use: Regular Expressions
Next to the search box there is now an arrow that is active, it will show you available RegEx options/values.
The value you want will be \n. So "SearchValue\n" should do it.
Be aware that that its not a standard RegEx that you use, it's VS specific.
Replace can also use the RegEx values.
Adding on to Brian Schmitt's answer...
Regular expression searches using \n work as expected. However you have to be a little careful when using \n in regex replaces with Visual Studio 2008. For example, if you search for \n and replace with \n (yes, the exact same thing) all of the line breaks in your file(s) will be converted to Unix-style newlines (LF). This may be a bug in Visual Studio. I find it hard to believe this is the intended functionality.
To get around this, you can use tagged expressions, using curly braces: e.g. search for SearchValue{\n} and replace with ReplaceValue\1. This ensures that the same line-break character(s) that were found when searching will also be used when replacing.
You can try my Multiline Search and Replace Macro.