2019-04-20 02:51
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I am building a super simple function to ensure a password contains specific characters. Namely, the password should have the following:

  • One lowercase letter
  • One uppercase letter
  • One digit
  • One special character
  • No white space, #, or |

I thought regex would be the simplest way to go about doing this. But, I am having a hard time figuring out how to do this in Golang. Currently, I have a bunch of separate regex MatchString functions which I will combine to get the desired functionality. For example:

lowercaseMatch := regexp.MustCompile(`[a-z]`).MatchString
uppercaseMatch := regexp.MustCompile(`[A-Z]`).MatchString
digitMatch := regexp.MustCompile(`\d`).MatchString
specialMatch := regexp.MustCompile(`\W`).MatchString
badCharsMatch := regexp.MustCompile(`[\s#|]`).MatchString
if (lowercaseMatch(pwd) 
        && uppercaseMatch(pwd) 
        && digitMatch(pwd)
        && specialMatch(pwd)
        && !badCharsMatch(pwd)) {
    /* password OK */
} else {
    /* password BAD */

While this makes things pretty readable, I would prefer a more concise regex, but I don't know how to get regex to search for a single character of each of the above categories (regardless of position). Can someone point me in the right direction of how to achieve this? Additionally, if there is a better way to do this than regex, I am all ears.


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1条回答 默认 最新

  • doubi8965 2019-04-20 03:28

    Since golang use re2, it doesn't support positive-lookahead (?=regex), so I'm not sure if there is a way to write a regex that cover all cases.

    Instead, you can use unicode package:

    func verifyPassword(s string) bool {
        var hasNumber, hasUpperCase, hasLowercase, hasSpecial bool
        for _, c := range s {
            switch {
            case unicode.IsNumber(c):
                hasNumber = true
            case unicode.IsUpper(c):
                hasUpperCase = true
            case unicode.IsLower(c):
                hasLowercase = true
            case c == '#' || c == '|':
                return false
            case unicode.IsPunct(c) || unicode.IsSymbol(c):
                hasSpecial = true
        return hasNumber && hasUpperCase && hasLowercase && hasSpecial
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