Question

目前，我正在使用它：

if (preg_match ('/^[a-zA-Z0-9_]+([a-zA-Z0-9_]*[.-]?[a-zA-Z0-9_]*)*[a-zA-Z0-9_]+$/', $product) ) {
return true;
} else { 
return false
}

例如，我想匹配：

pro.duct-name_
_pro.duct.name
p.r.o.d_u_c_t.n-a-m-e

但我不想匹配：

pro..ductname
.productname-
-productname.
-productname

Answer 1

答案是

/^[a-zA-Z0-9_]+([-.][a-zA-Z0-9_]+)*$/

如果只允许包含.-和-.的字符串不匹配。无论如何，你为什么要允许它们匹配？但如果你真的需要这些字符串来匹配，可能的解决方案是

/^[a-zA-Z0-9_]+((\.(-\.)*-?|-(\.-)*\.?)[a-zA-Z0-9_]+)*$/

第一个正则表达式的单个.或-被替换为一系列交替的.和-，从.或{{开始1}}，可选地分别后跟-或-.对，可选地分别后跟.-或-，以允许偶数个交替的字符。这种复杂性可能是一种过冲，但目前的规范似乎需要这种复杂性。如果需要最多2个交替.和.，则正则表达式变为

测试here或here

Answer 2

试试这个

(?im)^([a-z_][\w\.\-]+)(?![\.\-])\b

更新1

(?im)^([a-z_](?:[\.\-]\w|\w)+(?![\.\-]))$

更新2

(?im)^([a-z_](?:\.\-\w|\-\.\w|\-\w|\.\w|\w)+)$

<强>解释

<!--
(?im)^([a-z_](?:\.\-\w|\-\.\w|\-\w|\.\w|\w)+)$

Match the remainder of the regex with the options: case insensitive (i); ^ and $ match at line breaks (m) «(?im)»
Assert position at the beginning of a line (at beginning of the string or after a line break character) «^»
Match the regular expression below and capture its match into backreference number 1 «([a-z_](?:\.\-\w|\-\.\w|\-\w|\.\w|\w)+)»
   Match a single character present in the list below «[a-z_]»
      A character in the range between “a” and “z” «a-z»
      The character “_” «_»
   Match the regular expression below «(?:\.\-\w|\-\.\w|\-\w|\.\w|\w)+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
      Match either the regular expression below (attempting the next alternative only if this one fails) «\.\-\w»
         Match the character “.” literally «\.»
         Match the character “-” literally «\-»
         Match a single character that is a “word character” (letters, digits, and underscores) «\w»
      Or match regular expression number 2 below (attempting the next alternative only if this one fails) «\-\.\w»
         Match the character “-” literally «\-»
         Match the character “.” literally «\.»
         Match a single character that is a “word character” (letters, digits, and underscores) «\w»
      Or match regular expression number 3 below (attempting the next alternative only if this one fails) «\-\w»
         Match the character “-” literally «\-»
         Match a single character that is a “word character” (letters, digits, and underscores) «\w»
      Or match regular expression number 4 below (attempting the next alternative only if this one fails) «\.\w»
         Match the character “.” literally «\.»
         Match a single character that is a “word character” (letters, digits, and underscores) «\w»
      Or match regular expression number 5 below (the entire group fails if this one fails to match) «\w»
         Match a single character that is a “word character” (letters, digits, and underscores) «\w»
Assert position at the end of a line (at the end of the string or before a line break character) «$»
-->

你可以测试它here。

Answer 3

这应该做：

/^[A-z0-9_]([.-]?[A-Z0-9_]+)*[.-]?[A-z0-9_]$/

它将确保单词以字母数字或下划线字符开头和结尾。中间的括号将确保连续最多只有一个句点或破折号，后跟至少一个字母数字或下划线字符。

Answer 4

/^[A-Z0-9_][A-Z0-9_.-]*[A-Z0-9_]$/i

这可确保第一个和最后一个字符不是破折号或句号;中间的其余部分可能包含任何字符（在您选择的集合中）。

Answer 5

下面的正则表达式将检查包含字符，数字，短划线等的任何字符串，并且中间只有一个点。

/^[A-Za-z0-9_-]+(\.){1}[A-Za-z0-9_-]+$/i

希望这会有所帮助

正则表达式匹配字母数字字符，下划线，句点和破折号，只允许点和破折号在中间

5 个答案: