正则表达式忽略字符后的所有内容

Question

I have following regex.

^(.*[^0-9])([0-9A-Fa-f]{8}[-]?[0-9A-Fa-f]{4}[-]?[0-9A-Fa-f]{4}[-]?[0-9A-Fa-f]{4}[-]?[0-9A-Fa-f]{12})(.*)$

It splits a given text into 3 groups. 1:Pre-GUID , 2:GUID and 3:post-GUID text.

Input: /user/questions/9c8a8823-d88c-4402-a2c1-4530a966f993/help

Results:
Group 1: /user/questions/
Group 2: 9c8a8823-d88c-4402-a2c1-4530a966f993
Group 3: /help

However, I have some instances where GUID is followed by a special character such as @ and in that case I want to ignore everything after GUID ignored ie 3rd group that is post GUID be empty.

Input: /user/questions/9c8a8823-d88c-4402-a2c1-4530a966f993@help

Results:
Group 1: /user/questions/
Group 2: 9c8a8823-d88c-4402-a2c1-4530a966f993
Group 3: 

In other terms i don't want regex to consider anything if it encounters a @ .

Answer 1

If you want the third group to be none , you may replace it with:

([^@:].*$)?

If you want the third group to be empty , you may use:

([^@:].*$|)

This will look for either @ or : . You may add more characters to the negated character class as needed.

Demo .

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There's one more improvement that I feel inclined to recommend though. Currently, your pattern will match GUID's that have hyphens in some places but not others. To fix this, we can add the first hyphen in a capturing group and replace the subsequent ones with a backreference:

^(.*[^0-9])([0-9A-Fa-f]{8}(-?)[0-9A-Fa-f]{4}\3[0-9A-Fa-f]{4}\3[0-9A-Fa-f]{4}\3[0-9A-Fa-f]{12})([^@:].*$)?

Demo .

Note that in this case, the last part will be in group 4 instead of group 3.

Answer 2

If I understand you correctly, if the last part of the string is :<whatever> or @<whatever> the group 3 should be empty:

^(.*[^0-9])([0-9A-Fa-f]{8}[-]?[0-9A-Fa-f]{4}[-]?[0-9A-Fa-f]{4}[-]?[0-9A-Fa-f]{4}[-]?[0-9A-Fa-f]{12})([^:@].*$|)

Regex demo.

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Only the last group is changed to ([^:@].*$|) - match any character but : / @ to end of string or match empty string.