Ch3, lesson 1 - Forming Regular Expressions.

• Text processing - pattern matching, (sub)string extraction, (sub)string replacement.

Pattern Matching

• namespace - System.Text.RegularExpressions.
• statc mthd - System.Text.RegularExpressions.Regex.IsMatch(,);
• ^,$ - begin, end.
• \b - word boundary.
• \B - match NOT on a \b boundary.
• @ - backslashes are treated literally.
• * >=0
• + >=1
• {n} - repeat previous char n times.
• {n,m} - repeat prev char bet n & m times.
• {n,} - repeat previous char min n times.
• ? - prev. char optional.
• . - single char.
• [] - character class/range - e.g. [0-9] = \d
• \d - numeric digit, \D - non-numeric char - [^0-9]
• \s - white-space char, \S - non-white space char
• \w - word char = [a-zA-Z0-9_], \W - [^a-zA-Z0-9_]
• () - to match group of chars
• (?pattern) - name a group - to refer to matched data later.
• backreferencing - to find repeating groups of characters.
• (?\w)\k - finds doubled word characters.
• \1 - 1st backreference in a reg expr, \2 - 2nd backref in regex,...
• extract matched data - access elts of Match>Groups array.
• Replace substrings using reg expr...