(a|b)
(a|b)\1
What does \1 mean in this expression?
在这个表达式中，\1是什么意思?
2 个解决方案
#1
39
\1 - it means the first capturing group in the matched expression. \n would be the nth capturing group. (Note that \0 would be whole match). In many engines, the upperlimit for n is 9, but some support up to 99 as well.
\1 -它表示匹配表达式中的第一个捕获组。n将是第n个捕获组。(注意，\0将是完整的匹配)。在许多引擎中，n的上限是9，但也有一些支持高达99。
When used in regex like (a|b)\1, it means that after a or b, the next character should be the first captured group, which is a or b so the regex here would match aa or bb.
当在regex中使用(a|b)\1时，它意味着在a或b之后，下一个字符应该是第一个捕获的组，即a或b，因此这里的regex将匹配aa或bb。
#2
12
If refers to what was matched in the first set of parentheses, the first group. Subsequent number means subsequent parentheses.
如果指的是第一个括号集合中匹配的对象，即第一组。后面的数字表示后面的括号。
(1|2)(3|4)\1\2
Would match:
将匹配:
1313
1414
2323
2424
Not that if you have nested groups, just count from the opening brace (left brace).
如果你有嵌套的组，那就从左括号开始计算。
(groupOne(groupTwo)stillOne(groupThree(groupFour)))
What does What does 在这个表达式中，\1是什么意思? 39 \1 -它表示匹配表达式中的第一个捕获组。n将是第n个捕获组。(注意，\0将是完整的匹配)。在许多引擎中，n的上限是9，但也有一些支持高达99。 When used in regex like 当在regex中使用(a|b)\1时，它意味着在a或b之后，下一个字符应该是第一个捕获的组，即a或b，因此这里的regex将匹配aa或bb。 12 If refers to what was matched in the first set of parentheses, the first group. Subsequent number means subsequent parentheses. 如果指的是第一个括号集合中匹配的对象，即第一组。后面的数字表示后面的括号。 Would match: 将匹配: Not that if you have nested groups, just count from the opening brace (left brace). 如果你有嵌套的组，那就从左括号开始计算。(a|b)\1
\1 mean in this expression?2 个解决方案
#1
\1 - it means the first capturing group in the matched expression. \n would be the nth capturing group. (Note that \0 would be whole match). In many engines, the upperlimit for n is 9, but some support up to 99 as well.(a|b)\1, it means that after a or b, the next character should be the first captured group, which is a or b so the regex here would match aa or bb.#2
(1|2)(3|4)\1\2
1313
1414
2323
2424
(groupOne(groupTwo)stillOne(groupThree(groupFour)))
