Related knowledge of regular expression \w \d

After consulting many related regular descriptions, I found that the definition of \w refers to containing uppercase and lowercase letters, numbers and underscores, which is equivalent to ([0-9a-zA-Z]) (based on the classic tutorial Regular Rules 30-minute introductory tutorial on expressions)

However, in actual use, I found that this is not the case. It can also be said that it actually does not only include ([0-9a-zA-Z_]) these data,

The following is a test screenshot tool for editplus:

actually includes Greek letters and Russian letters in addition to ([0-9a-zA-Z_]) etc.;

So if you need to pay attention to the specific matching data when registering user information, you must not use it directly\wThat's it.

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