Regular expression for checking if capital letters are found consecutively in a string

Question

I want to know the regexp for the following case   The string should contain only alphabetic letters  It must start with a capital letter followed by small letter  Then it can be small letters or capital letters     A-Z  a-z  A-Za-z      But the string must also not contain any consecutive capital letters  How do I add that logic to the regexp   That is  HttpHandler is correct  but HTTPHandler is wrong

User · Answer

Aside from tchrists excellent post concerning unicode, I think you don't need the complex solution with a negative lookahead... Your definition requires an Uppercase-letter followed by at least one group of (a lowercase letter optionally followed by an Uppercase-letter)

^
[A-Z]    // Start with an uppercase Letter
(        // A Group of:
  [a-z]  // mandatory lowercase letter
  [A-Z]? // an optional Uppercase Letter at the end
         // or in between lowercase letters
)+       // This group at least one time
$

Just a bit more compact and easier to read I think...

User · Answer

If you want to get all Employee name in mysql which having at least one uppercase letter than apply this query   SELECT   FROM registration WHERE  name  REGEXP BINARY   A-Z

User · Answer

Whenever one writes  A-Z  or  a-z   one explicitly commits to processing nothing but 7-bit ASCII data from the 1960s   If that   s really ok  then fine   But if it   s not ok  then Unicode character properties exist to help you with handling modern character data  There are three cases in Unicode  not two  Furthermore  you also have noncased letters  Letters in general are specified by the  pL property  and  each of these also belongs to exactly one of five subcategories   uppercase letters  specified with  p Lu   eg  A     SSS  ST titlecase letters  specified with  p Lt   eg    Ss St  actually Ss and St are an upper- and then a lowercase letter  but they are what you get if you ask for the titlecase of    and    respectively  lowercase letters  specified with  p Ll   eg  aa    s       modifier letters  specified with  p Lm   eg            other letters  specified with  p Lo   eg         You can take the complement of any of these  but do be careful  because something like  P Lu  does not mean a letter that isn   t uppercase  It means any character that isn   t an uppercase letter  For a letter that   s either of uppercase or titlecase  use   p Lu  p Lt     So you could use for your pattern       p Lu  p Lt   p Ll       If you don   t mean to limit the letters following the first to the    casing    letters alone  then you might prefer       p Lu  p Lt    p Ll  p Lm  p Lo        If you   re trying to match so-called    CamelCase    identifiers  then the actual rules depend on the programming language  but usually include the underscore character and the decimal numbers   p Nd    and may also include a literal dollar sign and other language-dependent characters  If so  you may wish to add some of these to one or the other of the two character classes provided above  For example  you may wish to add underscore to both but digits only to the second  leaving you with        p Lu  p Lt     p Nd  p Ll  p Lm  p Lo        If  though  you are dealing with certain    words    from various RFCs and ISO standards  these are often specified as containing ASCII only   If so  you can get by with the literal  A-Z  idea  It   s just not kind to impose that restriction if it doesn   t actually exist

User · Answer

Edit  2015-10-26  thanks for the upvotes - but take a look at tchrist s answer  especially if you develop for the web or something more  international    Oren Trutners answer isn t quite right  see sample input of  RightHerE  which must be matched but isn t   Here is the correct solution          A-Z  2        A-Za-z      edit            A-Z  2           don t match the whole expression if there are two or more consecutive uppercase letters   A-Za-z                match uppercase and lowercase letters    edit  the key for the solution is a negative lookahead see  http   www regular-expressions info lookaround html

User · Answer

A-Z  a-z        This looks for sequences of an uppercase letter followed by one or more lowercase letters   Consecutive uppercase letters will not match  as only one is allowed at a time  and it must be followed by a lowercase one

[regex] Regular expression for checking if capital letters are found consecutively in a string?

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