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defines a range of characters..
matches any character.\
is used to escape the following character when that character is a special character. So, for example, a regular expression that found '.com' would be\\.com
because.
is a special character that matches any character.\d
matches any single digit.\w
matches any part of word character (equivalent to[A-Za-z0-9]
).\s
matches any space, tab, or newline.^
asserts the position at the start of the line. So what you put after it will only match if they are the first characters of a line.$
asserts the position at the end of the line. So what you put before it will only match if they are the last characters of a line.\b
adds a word boundary. Putting this either side of a stops the regular expression matching longer variants of words.*
matches the preceding element zero or more times. For example,ab*c
matches 'ac', 'abc', 'abbbc', etc.+
matches the preceding element one or more times. For example,ab+c
matches 'abc', 'abbbc' but not 'ac'.?
matches when the preceding character appears zero or one time.{VALUE}
matches the preceding character the number of times define by VALUE; ranges can be specified with the syntax{VALUE,VALUE}
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means or.