我正在寻找一个正则表达式来允许 6 个字符，并且在 6 个字符内，它应该只允许 3 个字母和 3 个数字

Question

我希望编写一个正则表达式以允许 6 个字符，并且在 6 个字符内，它应该只允许 3 个字母和 3 个数字。

Answer 1

Its like a password validation:

^(?=(?:.*[a-zA-Z]){3})(?=(?:.*[0-9]){3})[a-zA-Z0-9]{6}$

Anchor the begin and end of string forces 6 characters only.

 ^ 
 # Must have 3 letters
 (?=
    (?: .* [a-zA-Z] ){3}
 )
 # Must have 3 numbers
 (?=
    (?: .* [0-9] ){3}
 )
 # Must have 6 characters
 [a-zA-Z0-9]{6} 
 $