e444. matching across line boundaries in a regular expression.txt

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By default, the any-character matcher (.) does not match line termination characters such as \n and \r. To allow dot (.) to match line termination characters, the pattern should be compiled with the dotall flag enabled. 
It is also possible to enable dotall mode within a pattern using the inline modifier (?s). For example, dotall mode is enabled in the pattern (?s)a.*b. Dotall mode can be disabled using (?-s). 

    CharSequence inputStr = "abc\ndef";
    String patternStr = ".*c.+d.*";
    
    // Compile with dotall enabled
    Pattern pattern = Pattern.compile(patternStr, Pattern.DOTALL);
    Matcher matcher = pattern.matcher(inputStr);
    boolean matchFound = matcher.matches();    // true
    
    // Use an inline modifier to enable dotall mode
    matchFound = pattern.matches(".*c.+d.*", "abc\r\ndef");     // false
    matchFound = pattern.matches("(?s).*c.+d.*", "abc\r\ndef"); // true

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