Do I need to use regex to ensure that the user has typed in English? All characters are valid except non English characters.
How do I validate this textbox?
A regex would work quite well for this. Something like
^[a-zA-Z0-9 ?!.,;:$]*$
would be a good starting point. It would allow all alphabetical and numerical characters, as well as some common punctuation. You would need to change it depending on what your definition of English characters is.
See the regex docs here for more information.
This has nothing to do with regular expressions and the link referred to by gurukulki does not answer the question either. To change language, you need to implement localization in your website:
http://www.west-wind.com/presentations/wwdbResourceProvider/introtolocalization.aspxlink text
http://www.codeproject.com/KB/aspnet/localizationByVivekTakur.aspx
You might use the FilteredTextBox form ASP.NET AJAX.
Related
I am building a JavaScript array depending on the input of the user. The array is building fine but if the user enters Chinese symbols it crashes. I'm assuming that it is if the user enters a chinese " or a , or a '. I have the program replacing the English versions of this but i don't know how to replace the Chinese versions of it.
Can anyone help?
Thanks to all for their input
From What's the complete range for Chinese characters in Unicode?, the CJK unicode ranges are:
4E00-9FFF (common)
3400-4DFF (rare)
F900-FAFF (compatability - Duplicates, unifiable variants, corporate characters)
20000-2A6DF (rare, historic)
2F800-2FA1F (compatability - supplement)
Because JS strings only support UCS-2, which max out at FFFF, the last two ranges probably aren't of great interest. Thus, if you're building a JS string should be able to filter out chinese characters using something like:
replace(/[\u4e00-\u9fff\u3400-\u4dff\uf900-\ufaff]/g, '')
You need to use unicode replacer.
I think it will help you: http://answers.yahoo.com/question/index?qid=20080528045141AAJ0AIS
.Net provides JavaScriptSerializer and it's method Serialize, which creates correctly escaped JavaScript literals (although I personally haven't used it with Chinese characters, but there is no reason it shouldn't work).
Building on broofa's answer:
If you just want to find and replace the Chinese punctuation like " or " or a . then you'll want to use unicode characters in the range of FF00-FFEF. Here is a PDF from Unicode showing them: http://unicode.org/charts/PDF/UFF00.pdf
I think you'd want at least replace these: FF01, FF02, FF07, FF0C, FF0E, FF1F, and FF61. That should be the major Chinese punctuation marks. You can use broofa's replace function.
Not asked by the question, but adding \u30a0-\u30ff\u3040-\u309f you can also take out the Hiragana and Katakana from Japanese:
replace(/[\u4e00-\u9fff\u3400-\u4dff\uf900-\ufaff\u30a0-\u30ff\u3040-\u309f]/g, '')
https://regex101.com/r/4Aw9Q8/1
https://en.wikipedia.org/wiki/Katakana_(Unicode_block)
https://en.wikipedia.org/wiki/Hiragana_(Unicode_block)
What is the best way, in .NET, to create safe URLs from titles of posts?
For example, I may have a post "test wıth non enğlİşh çharaçters" and I want to turn this into a URL safe form while still maintaining the readability purpose of the title being URL, such as, "test-with-non-english-characters", and I will use them as http://mysite/blog/5/test-with-non-english-characters I can just iterate over the string characters and either leave ALL letters as they are (not safe to use in URLs), or wipe out all non-English characters and turn them into an underscore etc. (breaks the purpose of readability, as posts will/may be in non English languages). I'm sure that there's a method for converting ş to s and Ğ to G etc. just like in an accent insensitive search query in SQL server.
See my answer to another question to remove accents from a string.
Note that this doesn't completely solve the problem. For example, Asian ideograms or non latin letters will not be transliterated to english (latin) letters using this code.
I don't really know what to entitle this, but I need some help with regular expressions. Firstly, I want to clarify that I'm not trying to match HTML or XML, although it may look like it, it's not. The things below are part of a file format I use for a program I made to specify which details should be exported in that program. There is no hierarchy involved, just that each new line contains a 'tag':
<n>
This is matched with my program to find an enumeration, which tells my program to export the name value, anyway, I also have tags like this:
<adr:home>
This specifies the home address. I use the following regex:
<((?'TAG'.*):(?'SUBTAG'.*)?)?(\s+((\w+)=('|"")?(?'VALUE'.*[^'])('|"")?)?)?>
The problem is that the regex will split the adr:home tag fine, but fail to find the n tag because it lacks a colon, but when I add a ? or a *, it then doesn't split the adr:home and similar tags. Can anyone help? I'm sure it's only simple, it's just this is my first time at creating a regular expression. I'm working in C#, by the way.
Will this help
<((?'TAG'.*?)(?::(?'SUBTAG'.*))?)?(\s+((\w+)=('|"")?(?'VALUE'.*[^'])('|"")?)?)?>
I've wrapped the : capture into a non capturing group round subtag and made the tag capture non greedy
Not entirely sure what your aim is but try this:
(?><)(?'TAG'[^:\s>]*)(:(?'SUBTAG'[^\s>:]*))?(\s\w+=['"](?'VALUE'[^'"]*)['"])?(?>>)
I find this site extremely useful for testing C# regex expressions.
What if you put the colon as part of the second tag?
<((?'TAG'.*)(?':SUBTAG'.*)?)?(\s+((\w+)=('|"")?(?'VALUE'.*[^'])('|"")?)?)?>
I'd like to String.Split() the following string using a comma as the delimitter:
John,Smith,123 Main Street,212-555-1212
The above content is entered by a user. If they enter a comma in their address, the resulting string would cause problems to String.Split() since you now have 5 fields instead of 4:
John,Smith,123 Main Street, Apt 101,212-555-1212
I can use String.Replace() on all user input to replace commas with something else, and then use String.Replace() again to convert things back to commas:
value = value.Replace(",", "*");
However, this can still be fooled if a user happens to use the placeholder delimitter "*" in their input. Then you'd end up with extra commas and no asterisks in the result.
I see solutions online for dealing with escaped delimitters, but I haven't found a solution for this seemingly common situation. What am I missing?
EDIT: This is called delimitter collision.
This is a common scenario — you have some arbitrary string values that you would like to compose into a structure, which is itself a string, but without allowing the values to interfere with the delimiters in structure around them.
You have several options:
Input restriction: If it is acceptable for your scenario, the simplest solution is to restrict the use of delimiters in the values. In your specific case, this means disallow commas.
Encoding: If input restriction is not appropriate, the next easiest option would be to encode the entire input value. Choose an encoding that does not have delimiters in its range of possible outputs (e.g. Base64 does not feature commas in its encoded output)
Escaping delimiters: A slightly more complex option is to come up with a convention for escaping delimiters. If you're working with something mainstream like CSV it is likely that the problem of escaping is already solved, and there's a standard library that you can use. If not, then it will take some thought to come up with a complete escaping system, and implement it.
If you have the flexibility to not use CSV for your data representation this would open up a host of other options. (e.g. Consider the way in which parameterised SQL queries sidestep the complexity of input escaping by storing the parameter values separately from the query string.)
This may not be an option for you but would is it not be easier to use a very uncommon character, say a pipe |, as your delimiter and not allow this character to be entered in the first instance?
If this is CSV, the address should be surrounded by quotes. CSV parsers are widely available that take this into account when parsing the text.
John,Smith,"123 Main Street, Apt. 6",212-555-1212
One foolproof solution would be to convert the user input to base64 and then delimit with a comma. It will mean that you will have to convert back after parsing.
You could try putting quotes, or some other begin and end delimiters, around each of the user inputs, and ignore any special character between a set of quotes.
This really comes down to a situation of cleansing user inputs. You should only allow desired characters in the user input and reject/strip invalid inputs from the user. This way you could use your asterisk delimiter.
The best solution is to define valid characters, and reject non valid characters somehow, then use the nonvalid character (which will not appear in the input since they are "banned") as you delimiters
Dont allow the user to enter that character which you are using as a Delimiter. I personally feel this is best way.
Funny solution (works if the address is the only field with coma):
Split the string by coma. First two pieces will be name and last name; the last piece is the telephone - take those away. Combine the rest by coma back - that would be address ;)
In a sense, the user is already "escaping" the comma with the space afterward.
So, try this:
string[] values = RegEx.Split(value, ",(?![ ])");
The user can still break this if they don't put a space, and there is a more foolproof method (using the standard CSV method of quoting values that contain commas), but this will do the trick for the use case you've presented.
One more solution: provide an "Address 2" field, which is where things like apartment numbers would traditionally go. User can still break it if they are lazy, though what they'll actually break the fields after address2.
Politely remind your users that properly-formed street addresses in the United States and Canada should NEVER contain any punctuation whatsoever, perhaps?
The process of automatically converting corrupted data into useful data is non-trivial without heuristic logic. You could try to outsource the parsing by calling a third-party address-formatting library to apply the USPS formatting rules.
Even USPS requires the user to perform much of the work, by having components of the address entered into distinct fields on their address "canonicalizer" page (http://zip4.usps.com/zip4/welcome.jsp).
I need to implement something similar to wikilinks on my site. The user is entering plain text and will enter [[asdf]] wherever there is an internal link. Only the first five examples are really applicable in the implementation I need.
Would you use regex, what expression would do this? Is there a library out there somewhere that already does this in C#?
On the pure regexp side, the expression would rather be:
\[\[([^\]\|\r\n]+?)\|([^\]\|\r\n]+?)\]\]([^\] ]\S*)
\[\[([^\]\|\r\n]+?)\]\]([^\] ]\S*)
By replacing the (.+?) suggested by David with ([^\]\|\r\n]+?), you ensure to only capture legitimate wiki links texts, without closing square brackets or newline characters.
([^\] ]\S+) at the end ensures the wiki link expression is not followed by a closing square bracket either.
I am note sure if there is C# libraries already implementing this kind of detection.
However, to make that kind of detection really full-proof with regexp, you should use the pushdown automaton present in the C# regexp engine, as illustrated here.
I don't know if there are existing libraries to do this, but if it were me I'd probably just use regexes:
match \[\[(.+?)\|(.+?)\]\](\S+) and replace with \1\3
match \[\[(.+?)\]\](\S+) and replace with \1\2
Or something like that, anyway.
Although this is an old question and already answered, I thought I'd add this as an addendum for anyone else coming along. The existing two answers do all the real work and got me 90% there, but here is the last bit for anyone looking for code to get straight on with trying:
string html = "Some text with a wiki style [[page2.html|link]]";
html = Regex.Replace(html, #"\[\[([^\]\|\r\n]+?)\|([^\]\|\r\n]+?)\]\]([^\] ]\S*)", #"$2$3");
html = Regex.Replace(html, #"\[\[([^\]\|\r\n]+?)\]\]([^\] ]\S*)", #"$1$2");
The only change to the actual regex is I think the original answer had the replacement parts the wrong way around, so the href was set to the display text and the link was shown on the page. I've therefore swapped them.