I want to validate full name in contact form. I want to restrict spaces in alphabets. textbox should only accept a-z characters.
I used this regular expression
ValidationExpression="[a-zA-Z ]*$"
But it allows spaces also.
Your regex doesn't work because it contains spaces in the character squance.
You can specify the pattern correctly as
ValidationExpression="^[a-z]*$"
^ Anchors the regex at the start of the string.
[a-z]* Matches zero or more characters
$ Anchors the regex at the end of the string.
Regex Demo
EDIT
To restrict the characters to 50 we could use a quantifier as
ValidationExpression="^[a-z]{,50}$"
{,50} Quantifier ensures that there can be a maximum of 50 characters.
Just remove the space inside your character class?
Also anchor the regex so that it matches at the start of a line :
^[a-zA-Z]*$
And take into consideration that ^ and $ can be influenced by the modifier that says it should match at a newline or not
I would just use "^[a-zA-Z]+$".
I think the issue you have is there is a space between the Z and ]. When I tested this it allowed spaces into the regular expression. I also changed the * to + to not allow a blank string.
Related
I would like to create a custom regular expression. Which shall track that the first character of a username should be an alphabet.
Followed by alphanumeric or can have maximum one occurrence of a special character (- or _). I can check for username starts with the alphabet with this ^[a-zA-Z]+$ but not sure what to do to check at most one occurrence of a special character. Any ideas are welcome.
Thanks
From what I understood of your post, you want the following to match.
a-afdsafd
aafdsafd
aafdsa_fd
aafdsa-fd
aAfdsa-FD
And the following to not match:
aa-dsa-fd
aa-dsa_fd
-afdsafd
_afdsafd
Try /^[a-z](?:(?![a-z]+[\-_])[\-_])?[a-z]+(?:(?<![a-z]+[\-_])[\-_]?)[a-z]+?$/i
The i modifier enables case-insensitive matching.
The ^ and $ anchors ensure that the entire string matches our regex.
[a-z] checks that the first character is an alphabet.
(?:(?![a-z]+[\-_])[\-_])?) looks ahead to check that there is no "special character" used later and if there is none, we optionally match one special character.
[a-z]+ Match one or more alphabets.
(?:(?<![a-z]+[\-_])[\-_]?) does the same thing as 4 except it looks behind.
[a-z]+? Optionally match one or more alphabets.
https://regexr.com/3t86l
Edit: I noticed that aAfdsaFd_ should also match. The above does not match this. Slightly modifying #Wiktor Stribiżew's comment, ^[a-zA-Z][a-zA-Z0-9]*(?:[-_][a-zA-Z0-9]*)?$ seems to work fine with all cases. That's cleaner and more efficient. All credit to #Wiktor Stribiżew.
You could match an upper or lowercase character from the start of the string ^[a-zA-Z], match zero or more times alphanumeric [a-zA-Z0-9]* followed by an optional hyphen or underscore [-_]?.
At the end match zero or more times alphanumeric [a-zA-Z0-9]*$ until the end of the string.
^[a-zA-Z][a-zA-Z0-9]*[-_]?[a-zA-Z0-9]*$
I have a regex expression validation for an UI field:
^[a-z|A-Z|0-9|_|\-]+$
Now I need to allow spaces for the entry, so if I add space to the regex expression, like this:
^[a-z|A-Z|0-9|_| |\-]+$
It does allow spaces at the beginning, end and repeated spaces.
Could someone help me with this please?
I suggest you to remove the | symbol from the character class and also include \s instead of a whitespace.
#"^[a-zA-Z0-9_-]+(?:\s[a-zA-Z0-9_-]+)*$"
But \s matches newline characters also. So change \s to a whitespace in the above regex based upon your needs. The main thing here is the non-capturing group (?:\s[a-zA-Z0-9_-]+)* which matches,
a space \s and also the following one or more word or hyphen characters [a-zA-Z0-9_-]+, zero or more times (?:\s[a-zA-Z0-9_-]+)*.
DEMO
I'm trying to build a regular expression in c# to check whether a string follow a specific format.
The format i want is: [digit][white space][dot][letters]
For example:
123 .abc follow the format
12345 .def follow the format
123 abc does not follow the format
I write this expression but it not works completelly well
Regex.IsMatch(exampleString, #"^\d+ .")
^ matches the start of the string, and you got it right.
\d+ matches one or more digits, and you got that one right as well.
A space in a regex matches a literal space, so that works too!
However, a . is a wildcard and will match any one character. You will need to escape it with a backslash like this if you want to match a literal period: \..
To match letters now, you can use [a-z]+ right after the period.
#"^\d+ \.[a-z]+"
The dot is a special character in regex, which matches any character (except, typically, newlines). To match a literal ., you need to escape it:
Regex.IsMatch(exampleString, #"^\d+ \.")
If you want to include the condition for the succeeding letters, use:
Regex.IsMatch(exampleString, #"^\d+ \.[A-Za-z]+$")
For you to get yours to match, keep in mind that the period in regular expressions is a special character that will match any character, so you'll need to escape that.
In addition, \s is a match for any white-space character (tabs, line breaks).
^\d+\s+ \..+
(untested)
I have a problem with that regular expression [^%()*+-\/=?#[\\]ªº´¿'.]*` .
I want to avoid the characters inside. the regular expression it is working but when I set something like DAVID, SC I can save the form because it has a comma but this character it is not inside the regular expression.
Could you help me please?
You are not accounting for the special meaning of - inside a character class [.....].
You must either place the dash at the very end, or else escape it with a backslash:
[^%()*+\/=?#\[\]ªº´¿'.-]*
In your original regex, +-\/ disallows any characters between + and / in the ASCII table; these are the comma, dot and dash. Your example input contains a comma so the regex did not match all of the input at once.
I have also fixed the escaping for the [] characters from [\\] to \[\], which I presume was a mistake.
Because you're using * in [^%()*+\/=?#[\\]ªº´¿'.-]* with line start/end anchors. * means match 0 or more of preceding group/pattern in character class and your regex can even match an empty string.
Use this regex:
^[^%()*+\/=?#[\\-]ªº´¿'.]+$
PS: Hyphen - should be either or first OR at last position in character class to avoid escaping.
Rubular Demo
What is the regular exp for a text that can't contain any special characters except space?
Because Prajeesh only wants to match spaces, \s will not suffice as it matches all whitespace characters including line breaks and tabs.
A character set that should universally work across all RegEx parsers is:
[a-zA-Z0-9 ]
Further control depends on your needs. Word boundaries, multi-line support, etc... I would recommend visiting Regex Library which also has some links to various tutorials on how Regular Expression Parsing works.
[\w\s]*
\w will match [A-Za-z0-9_] and the \s will match whitespaces.
[\w ]* should match what you want.
Assuming "special characters" means anything that's not a letter or digit, and "space" means the space character (ASCII 32):
^[A-Za-z0-9 ]+$
You need #"^[A-Za-z0-9 ]+$". The \s character class matches things other than space (such as tab) and you since you want to match sure that no part of the string has other characters you should anchor it with ^ and $.
If you just want alphabets and spaces then you can use: #"[A-Za-z\s]+" to match at least one character or space. You could also use #"[A-Za-z ]+" instead without explicitly denoting the space.
Otherwise please clarify.
In C#, I'd believe it's ^(\w|\s)*$