Regular expression for "This Specific A" formatting rule

Question

I'm trying to find the regex expression that validates a specific rule, but I'm quite a beginner with regular expressions.

Rule

There can be any number of words
Words are space-separated
Words only contain letters
Words start with a capital
The last word must be a single capitalized character

Expression

Here is where I am so far: ([A-Z][a-z]+[ ]*)*[A-Z]

Examples

Match

Example Name A
A New Example C

No match

a Test B
Wrong Name
Another_Wrong_Name A
Nop3 A

`^([A-Z][a-z]* )*[A-Z]$` ([demo](https://regex101.com/r/ewbFLZ/1))? — Wiktor Stribiżew, May 18 '21 at 11:36

score 1 · Accepted Answer · answered May 18 '21 at 11:44

Notes:

Your regex matches words with two or more letters only before the final one-letter word. You need to match one or more letter words using [A-Z][a-z]*
You use a character class, [ ], to match a single space, and this is redundant, remove brackets.
You need to match the entire string, with anchors, ^ and $, or \A and \z/\Z (depending on regex flavor).

You can use

^([A-Z][a-z]* )*[A-Z]$
^(?:[A-Z][a-z]* )*[A-Z]$
^(?:[A-Z][a-z]*\h)*[A-Z]$
^(?:[A-Z][a-z]*[^\S\r\n])*[A-Z]$

Note [^\S\r\n] and \h match horizontal whitespace, not just a regular space.

The non-capturing group, (?:...), is used merely for grouping patterns without keeping the text they matched in the dedicated memory slot, which is best practice, especially with repeated groups.

See this regex demo.