How to check if string has letter in second character with regex











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0
down vote

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Say I wanted to create an ID number such as 1A45 or 4F01.



What would the regex be to make sure that the string had exactly one letter as the second character?



I am unsure how to check for specific combinations of characters.



What I have so far is:



if(!Regex.IsMatch(txtTrainID.Text, @"^[w,d,w,w]+$"))


Which is obviously completely wrong, I've had trouble trying to find a decent simple answer to this anywhere.










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  • What about other three characters? I guess you have X/Y problem.
    – JohnyL
    Dec 2 at 11:50















up vote
0
down vote

favorite












Say I wanted to create an ID number such as 1A45 or 4F01.



What would the regex be to make sure that the string had exactly one letter as the second character?



I am unsure how to check for specific combinations of characters.



What I have so far is:



if(!Regex.IsMatch(txtTrainID.Text, @"^[w,d,w,w]+$"))


Which is obviously completely wrong, I've had trouble trying to find a decent simple answer to this anywhere.










share|improve this question
























  • What about other three characters? I guess you have X/Y problem.
    – JohnyL
    Dec 2 at 11:50













up vote
0
down vote

favorite









up vote
0
down vote

favorite











Say I wanted to create an ID number such as 1A45 or 4F01.



What would the regex be to make sure that the string had exactly one letter as the second character?



I am unsure how to check for specific combinations of characters.



What I have so far is:



if(!Regex.IsMatch(txtTrainID.Text, @"^[w,d,w,w]+$"))


Which is obviously completely wrong, I've had trouble trying to find a decent simple answer to this anywhere.










share|improve this question















Say I wanted to create an ID number such as 1A45 or 4F01.



What would the regex be to make sure that the string had exactly one letter as the second character?



I am unsure how to check for specific combinations of characters.



What I have so far is:



if(!Regex.IsMatch(txtTrainID.Text, @"^[w,d,w,w]+$"))


Which is obviously completely wrong, I've had trouble trying to find a decent simple answer to this anywhere.







c# regex






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edited Dec 2 at 11:40









Jan

24k52347




24k52347










asked Nov 14 at 7:33









ESuth

646




646












  • What about other three characters? I guess you have X/Y problem.
    – JohnyL
    Dec 2 at 11:50


















  • What about other three characters? I guess you have X/Y problem.
    – JohnyL
    Dec 2 at 11:50
















What about other three characters? I guess you have X/Y problem.
– JohnyL
Dec 2 at 11:50




What about other three characters? I guess you have X/Y problem.
– JohnyL
Dec 2 at 11:50












1 Answer
1






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up vote
4
down vote



accepted










If that's the only requirement (and I am sure it's not), use anchors and a character class in the second position as in



^.[A-Za-z]


See a demo on regex101.com.




What you probably mean, comes down to:

^d[a-zA-Z]d{2}$


The latter means one digit, one of a-zA-Z, followed by two other digits and the end of the string. See another demo on the same site.






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    1 Answer
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    active

    oldest

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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    4
    down vote



    accepted










    If that's the only requirement (and I am sure it's not), use anchors and a character class in the second position as in



    ^.[A-Za-z]


    See a demo on regex101.com.




    What you probably mean, comes down to:

    ^d[a-zA-Z]d{2}$


    The latter means one digit, one of a-zA-Z, followed by two other digits and the end of the string. See another demo on the same site.






    share|improve this answer

























      up vote
      4
      down vote



      accepted










      If that's the only requirement (and I am sure it's not), use anchors and a character class in the second position as in



      ^.[A-Za-z]


      See a demo on regex101.com.




      What you probably mean, comes down to:

      ^d[a-zA-Z]d{2}$


      The latter means one digit, one of a-zA-Z, followed by two other digits and the end of the string. See another demo on the same site.






      share|improve this answer























        up vote
        4
        down vote



        accepted







        up vote
        4
        down vote



        accepted






        If that's the only requirement (and I am sure it's not), use anchors and a character class in the second position as in



        ^.[A-Za-z]


        See a demo on regex101.com.




        What you probably mean, comes down to:

        ^d[a-zA-Z]d{2}$


        The latter means one digit, one of a-zA-Z, followed by two other digits and the end of the string. See another demo on the same site.






        share|improve this answer












        If that's the only requirement (and I am sure it's not), use anchors and a character class in the second position as in



        ^.[A-Za-z]


        See a demo on regex101.com.




        What you probably mean, comes down to:

        ^d[a-zA-Z]d{2}$


        The latter means one digit, one of a-zA-Z, followed by two other digits and the end of the string. See another demo on the same site.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 14 at 7:35









        Jan

        24k52347




        24k52347






























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