RegEx for name: Any language but first letter must be capital

Question

I have a requirement to accept a first name as input and check that the first letter is caps and that there can be 1 space after the end of the string.

This RegEx works for 'Bob ':

^[A-Z][A-Za-z\p{L}]+[\s,.'\-]?[a-zA-Z\p{L}]*$

An extra requirement is then to allow any language / character which then involves allowing unicode.

This RegEx works for a russian name: 'Афанасий'

^[A-Z\p{L}][A-Za-z\p{L}]+[\s,.'\-]?[a-zA-Z\p{L}]*$

... However, while it allows for unicode, it also allows me to enter 'bob' with a small first letter and the RegEx allows this through.

Is there any way to allow both unicode and still flag up the first letter when it is not capital? ( Using a RegEx)

I could make some code changes to get round this issue but it would be nice to be able to keep it all in the RegEx value without making code changes.

Answer 1

Any Unicode uppercase letter can be matched with \p{Lu}.

Use

^\p{Lu}\p{L}+[\s,.'\-]?\p{L}*$

or

^\p{Lu}\p{L}+(?:[\s,.'-]\p{L}+)?$

See the regex demo 1 and regex demo 2. The second regex is more precise as it won't allow trailing whitespace, comma, etc. (what is defined in the [\s,.'-] character class).

Note that there is no point in using [A-Za-z\p{L}] since \p{L} already matches [a-zA-Z].

Pattern details:

• ^ - start of string
• \p{Lu} - an uppercase Unicode letter
• \p{L}+ - one or more Unicode characters
• (?:[\s,.'-]\p{L}+)? - one or zero (optional) sequence of
  • [\s,.'-] - a whitespace, ,, ., ' or a hyphen
  • \p{L}+ - 1 or more Unicode letters
• $ - end of string.