RegEx that must have at least 3 alpha characters

I'm trying to create a expression to check that a response has at least three lette开发者_运维问答rs. Numbers, spaces and all other characters are valid. What I have below only works if a special character doesn't come first.

(?=(.*[a-zA-Z]){3,})^[a-zA-Z0-9].+$

You can use a much simpler regex: ([a-zA-Z].*?){3}

This matches a letter, optionally followed by other characters, repeated three times.

(?:[a-zA-Z][^a-zA-Z]*){3}

Matches (a letter, followed by any non-letters) 3 times. The (?:) makes it a little more efficient because the regex engine does not have to capture.

Of course it might be easier to read and understand without the regex. Here's C#/linq example.

if (s.Count(char.IsLetter) >= 3)
{
   // is valid.
}

My solution: (.*[a-zA-Z].*){3}

It is pretty similar to @SLaks'; the difference is that my code works if you have alpha characters enclosed in special characters like <script>.

@ridgerunner has a neat solution, but if the end of the string is an special character it won't match. You can see the example in this image:

None of the answers use the correct definition of a letter.

A letter is not [a-zA-Z]. Here's the Unicode category of lowercase letters: https://www.compart.com/en/unicode/category/Ll

It includes 2,155 entries, because latin is not the only alphabet in the world. For example, the Ukrainian phrase "Слава Україні!" doesn't pass the [a-zA-Z]+ regex. (https://regex101.com/r/n7PINx/1)

To correctly classify letters, use the unicode letter category with the \p{L} element: \p{L}{3} matches at least three letters, therefore the regex (\p{L}.*?){3} will match any string that has at least three letters. Additionally, you might want to anchor the regex to make sure it's the whole string that gets matched: ^(.*?\p{L}.*?){3}$ (https://regex101.com/r/sQQXtR/1).

Saying \p{L} is much more robust than [a-zA-Z], and also more self-explanatory – it's the letter group, not "these particular range of ASCII".