I want to do the following with regular expressions but not sure how to do it. I want it to match one two when one two is the beginning of the line unless the string contains three anywhere after one two.
我想用正则表达式执行以下操作，但不确定如何执行此操作。我希望它匹配一个二，当一个两个是行的开头，除非字符串包含三个在两个之后的任何地方。
2 个解决方案
#1
14
You need a negative lookahead assertion - something like this:
你需要一个负面的先行断言 - 像这样：
/^one two(?!.*three)/m
Here's a tutorial on lookahead/lookbehind assertions
这是一个关于前瞻/后瞻断言的教程
Note: I've added the 'm' modifier so that ^ matches the start of a line rather than the start of the whole string.
注意：我添加了'm'修饰符，以便^匹配行的开头而不是整个字符串的开头。
#2
4
^one two(?!.*three)
#1
14
You need a negative lookahead assertion - something like this:
你需要一个负面的先行断言 - 像这样：
/^one two(?!.*three)/m
Here's a tutorial on lookahead/lookbehind assertions
这是一个关于前瞻/后瞻断言的教程
Note: I've added the 'm' modifier so that ^ matches the start of a line rather than the start of the whole string.
注意：我添加了'm'修饰符，以便^匹配行的开头而不是整个字符串的开头。
#2
4
^one two(?!.*three)