java

• special characters with special meaning
• Escape special characters: not interpret special characters with their special meaning, force them to be treated as ordinary Characters
  

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  String input = "foof"; String regex = "foo."; input.matches(regex); // true

Here, the special meaning of dot is that it can be any character in its place.

• Escape special characters by using double backslashes
  • why not single? backslash is an escape character in Java String literals as well. -> double backslashes

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String input = "foof";
String regex = "foo\.";
input.matches(regex); // false