I want a regular expression to allow first character be an alphabet and then numbers only with following constraints :
-no space
-no special characters
like AS2, Nf2, nf_2, nf 08 should not be allowed.
'N00044,n0,n09,n099,123456,123' allowed
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`^[a-zA-Z]\d*$` , or `^[a-zA-Z]\d+$` if you want to ensure there is at least one number present. Have you tried anything yet? – Tim Biegeleisen Feb 08 '17 at 06:23
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Should there be both capitals and lowercase allowed? In your question it isn't clear what is and what isn't – JChrist Feb 08 '17 at 06:24
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yes(1st char only) – Feb 08 '17 at 06:25
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@TimBiegeleisen already gave you the answer in his comment above. `*` means zero or more times, `+` means 1 or more times. Pick what you need. – JChrist Feb 08 '17 at 06:26
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cehck this one https://regex101.com/r/R8dHTY/3 – Kaushik Thanki Feb 08 '17 at 06:34
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@KaushikThanki your regex also matches an alphabet following the first alphabet and hence doesn't meet the criteria. – Dhaval Simaria Feb 08 '17 at 06:36
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@DhavalSimaria i not sure , can give me some sample which fails my regex – Kaushik Thanki Feb 08 '17 at 06:39
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`NF2` for instance, @KaushikThanki – Jarvis Feb 08 '17 at 06:41
2 Answers
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You can try this regex :
^[A-z]\d+$
if you want a minimum of 1 digit necessary, or
^[A-z]\d*$
if having a digit is not mandatory.
Jarvis
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Depending on the flavor of regex, your query might not match both lowercase and uppercase characters in the first position. – Tim Biegeleisen Feb 08 '17 at 06:29
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Yes, I purposely mentioned that regex since alphanumeric include both uppercase as well as lowercase letters. @TimBiegeleisen – Jarvis Feb 08 '17 at 06:31
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2Nice trick, didn't know that `[A-z]` covers both upper and lower case +1 – Tim Biegeleisen Feb 08 '17 at 06:33
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For those who might be interested, `[a-Z]` won't work because `Z` comes before `a` in the character sequence. – Tim Biegeleisen Feb 08 '17 at 06:36
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@Jarvis above is correct could you tell me check above or all numeric characters 'N00044' or '123456' is correct – Feb 08 '17 at 06:50
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@Jarvis check above or all numeric characters i.e 'N00044' or '123456' is correct (adding numeric char) either the above works or all numeric condition – Feb 08 '17 at 06:54
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Jarvis's does meet the requirement but you can also use numeric range for the same since \d is specifically used for ASCII numbers. Refer when to use \d and [0-9].
Since numbers are required to be matched in your regex I would prefer as follows:
^([A-z][0-9]+)$
As per your requirement in comments, following regex should do the work for you:
^(([A-z][0-9]+)|([0-9]+))$
It will match an input with alphabet followed by numbers or an input with only numbers.
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Dhaval Simaria
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could you tell me check above or all numeric characters i.e 'N00044' or '123456' is correct (adding numeric char) either the above works or all numeric conditions – Feb 08 '17 at 06:52
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@AkhilJain Will you please elaborate. I didn't understand your question in comment properly. – Dhaval Simaria Feb 08 '17 at 06:57
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@AkhilJain Updated the answer as per your requirements in comments. – Dhaval Simaria Feb 08 '17 at 07:06
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1@AkhilJain Please check the answer and the test-case link now. I have updated it. – Dhaval Simaria Feb 08 '17 at 07:20