正则表达式验证问题

Question

I'm using the

^(?=^.{14,30}$)(?=^.[\d]{3}$)(?=^.[a-z]{4}$)(?=^.[A-Z]{5}$)(?=^.[!*&#$%^]{2}).$

regular expression in order to validate the following as minimum requirements:

1. Four low case letter
2. Five Upper case letters
3. Three digits
4. Two special characters
5. With total length between 14 to 30 characters long

But Unfortunately This validation pattern doesn't validate my string.
I've look for regex pattern validation and gives me that the pattern is OK
Can someone give me a support on this?

Answer 1

Note that (?=^.[az]{4}$) requires a match of a 5 char string where the first one csn be any char and then there must be 4 lowercase letters. In the end, after ^ and lookaheads, there is . before $ , so actually, the whole regex can match a single char string.

You may use

^(?=(?:\D*\d){3})(?=(?:[^a-z]*[a-z]){4})(?=(?:[^A-Z]*[A-Z]){5})(?=(?:[^!*&#$%^]*[!*&#$%^]){2}).{8,30}$

See the regex demo . A regulex graph :

Details

• ^ - start of string
• (?=(?:\\D*\\d){3}) - three occurrences of any 0+ non-digits followed with a digit
• (?=(?:[^az]*[az]){4}) - four occurrences of any 0+ chars other than a lowercase ASCII letters followed with a lowercase ASCII letter
• (?=(?:[^AZ]*[AZ]){5}) - five occurrences of any 0+ chars other than an uppercase ASCII letters followed with an uppercase ASCII letter
• (?=(?:[^!*&#$%^]*[!*&#$%^]){2}) - two occurrences of any 0+ chars other than some specific special chars (defined in the character class) followed with a char from the sepcified !*&#$%^ set
• .{8,30} - any 8 to 30 chars
• $ - end of string.

Answer 2

^(?=.{14,30}$)(?=(?:.*[A-Z]){5})(?=(?:.*[a-z]){4})(?=(?:.*\d){3})(?=(?:.*[!*&#$%^]){2}).*$
 └─────┬─────┘└───────┬────────┘└───────┬────────┘└──────┬──────┘└─────────┬──────────┘
       │              │                 │                │                 │
       │              │                 │                │        2 special characters
       │              │                 │                │
       │              │                 │            3 digits
       │              │                 │
       │              │          4 lowercase letters
       │              │ 
       │       5 uppercase letters
       │
string is 14-30 characters long 

---

^(?=(?:.*[A-Z]){5})(?=(?:.*[a-z]){4})(?=(?:.*\d){3})(?=(?:.*[!*&#$%^]){2}).(14,30)$
 └───────┬────────┘└───────┬────────┘└──────┬──────┘└─────────┬──────────┘
         │                 │                │                 │
         │                 │                │        2 special characters
         │                 │                │
         │                 │            3 digits
         │                 │
         │          4 lowercase letters
         │ 
  5 uppercase letters

Answer 3

Instead of a regex, which may be difficult to maintain, how about some simple code that is easy to read and modify:

Private Function IsStringValid(s As String) As Boolean
    If (s.Length > 30) OrElse (s.Length < 14) Then
        Return False
    End If

    Dim lower, upper, digit, special As Integer
    For Each c As Char In s
        Select Case True
            Case Char.IsLower(c)
                lower += 1
            Case Char.IsUpper(c)
                upper += 1
            Case Char.IsDigit(c)
                digit += 1
            Case Char.IsSymbol(c) OrElse Char.IsPunctuation(c)
                special += 1
        End Select
    Next
    Return (lower >= 4) AndAlso (upper >= 5) AndAlso (digit >= 3) AndAlso (special >= 2)
End Function

Based on your requirements, the minimum length has to be 14.