REGEX_USERNAME constant

String const REGEX_USERNAME

Regex of username.

scope for "a-z", "A-Z", "0-9", "_", "Chinese character"

can't end with "_"

length is between 6 to 20

Implementation

static const String REGEX_USERNAME      =
    "^[\\w\\u4e00-\\u9fa5]{6,20}(?<!_)\$";