字符串必须是字母数字并且包含某个子字符串

Question

我正在努力添加一个正则表达式来确定给定的输入是否有效。输入应为字母数字（也允许使用下划线、破折号、句点），并且介于 1 到 60 个字符之间。它还应该在其中包含某个子字符串（假设为“foo.bar”）。这是我的尝试：

^.[a-zA-Z0-9_.-]{1,60}$

除了子字符串部分，这就是我需要的。我不确定如何添加“字符串必须包含子字符串 foo.bar”要求。 FWIW 我在 Ruby 中这样做，所以我知道这意味着正在使用 PCRE。

例如，这个字符串应该是有效的：

aGreatStringWithfoo.barInIt1111

这不应该

aBadStringWithoutTheSubstringInIt

Answer 1

使用

^(?=.{1,60}$)[a-zA-Z0-9_.-]*foo\.bar[a-zA-Z0-9_.-]*$

参见regex proof。

解释

--------------------------------------------------------------------------------
  ^                        the beginning of the string
--------------------------------------------------------------------------------
  (?=                      look ahead to see if there is:
--------------------------------------------------------------------------------
    .{1,60}                  any character except \n (between 1 and
                             60 times (matching the most amount
                             possible))
--------------------------------------------------------------------------------
    $                        before an optional \n, and the end of
                             the string
--------------------------------------------------------------------------------
  )                        end of look-ahead
--------------------------------------------------------------------------------
  [a-zA-Z0-9_.-]*          any character of: 'a' to 'z', 'A' to 'Z',
                           '0' to '9', '_', '.', '-' (0 or more times
                           (matching the most amount possible))
--------------------------------------------------------------------------------
  foo                      'foo'
--------------------------------------------------------------------------------
  \.                       '.'
--------------------------------------------------------------------------------
  bar                      'bar'
--------------------------------------------------------------------------------
  [a-zA-Z0-9_.-]*          any character of: 'a' to 'z', 'A' to 'Z',
                           '0' to '9', '_', '.', '-' (0 or more times
                           (matching the most amount possible))
--------------------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string

字符串必须是字母数字并且包含某个子字符串

String must be alphanumeric and contain a certain substring

regex

pcre