What the mean of different symbols like ^, $, * , + , ?, ., {},[] in Regular Expressions

Question

Andrew Deniel · Answer

These symbols ^, $, * , + , ?, ., {},[] are very usefull like

"^PCDS": Symbols ^ use to matches any string that starts with "PCDS" this can match "PCDS is an Infotech";

"pcds$": Matches a string that ends in the substring "pcds" like "This is pcds";

"^pcds$": Matches a string that starts and ends with "pcds" that could only be "pcds" itself

"ab*": matches a string that has an a followed by zero or more b's ("a", "ab", "abbb", etc.);

"ab+": same as *, but there's at least one b ("ab", "abbb", etc.);

"ab?": there might be a b or not;

"ab.": . matches any character like abd, abh, abt etc;

"ab{2}": matches a string that has an a followed

by exactly two b's ("abb");

"ab{2,}": there are at least two b's ("abb", "abbbb", etc.);

"ab{3,5}": from three to five b's ("abbb", "abbbb", or "abbbbb").

"[a-z]": matches any char from a to z.

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