正则表达式：php 的密码验证

Question

我正在我的新项目中进行一些密码验证。我有这个规则，我想使用 php preg_match() 函数转换正则表达式模式：

• 接受所有字符。
• 空格除外。
• 最少 4 个字符。
• 最多 20 个字符。

提前谢谢您！

Answer 1

试试这个

(?s)^(\S{4,20})$

解释

"(?s)" +     // Match the remainder of the regex with the options: dot matches newline (s)
"^" +        // Assert position at the beginning of the string
"(" +        // Match the regular expression below and capture its match into backreference number 1
   "\\S" +       // Match a single character that is a “non-whitespace character”
      "{4,20}" +      // Between 4 and 20 times, as many times as possible, giving back as needed (greedy)
")" +
"$"          // Assert position at the end of the string (or before the line break at the end of the string, if any)

Answer 2

这会起作用。此声明中的唯一要求是至少 4 个、最多 20 个“允许”的字符。

/^[a-zA-Z0-9\W][\S]{4,20}$/

如果您希望每种类型至少需要一种：

/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*\W)[0-9A-Za-z\W][^\s]{4,20}$/

第二个选项解释：

//Look ahead for a lower case
(?=.*[a-z])

//Look ahead for an uppercase
(?=.*[A-Z])

//Look ahead for a number
(?=.*\d)

//Look ahead for a non-word character
(?=.*\W)

//Specify allowed characters (not space), minimum of 4, and maximum of 20 chars
[0-9A-Za-z\W][^\s]{4,20}