Regular expressions (regex or RegExp) consist of a combination of characters and special symbols that define a search pattern.
Here are some common patterns and symbols used in regex:
𝙇𝙞𝙩𝙚𝙧𝙖𝙡 𝘾𝙝𝙖𝙧𝙖𝙘𝙩𝙚𝙧𝙨:
◦ Regular characters, such as letters and digits, match themselves. For example, the pattern abc matches the string "abc" in the input.𝙈𝙚𝙩𝙖𝙘𝙝𝙖𝙧𝙖𝙘𝙩𝙚𝙧𝙨:
◦ Special characters that have a specific meaning in regex. Examples include:
▪ . (dot): Matches any single character except a newline.
▪ ^: Anchors the regex at the start of the string.
▪ $: Anchors the regex at the end of the string.𝘾𝙝𝙖𝙧𝙖𝙘𝙩𝙚𝙧 𝘾𝙡𝙖𝙨𝙨𝙚𝙨:
◦ Enclosed in square brackets [] and match any single character within the brackets. For example, [aeiou] matches any vowel.𝙌𝙪𝙖𝙣𝙩𝙞𝙛𝙞𝙚𝙧𝙨:
◦ Specify the number of occurrences of the preceding character or group. Examples include:
▪ *: Matches 0 or more occurrences.
▪ +: Matches 1 or more occurrences.
▪ ?: Matches 0 or 1 occurrence.
▪ {n}: Matches exactly n occurrences.
▪ {n,}: Matches n or more occurrences.
▪ {n,m}: Matches between n and m occurrences.𝙀𝙨𝙘𝙖𝙥𝙚 𝘾𝙝𝙖𝙧𝙖𝙘𝙩𝙚𝙧𝙨:
◦ The backslash \ is used to escape a metacharacter, allowing it to be treated as a literal character. For example, . matches a literal dot.𝙂𝙧𝙤𝙪𝙥𝙞𝙣𝙜 𝙖𝙣𝙙 𝘾𝙖𝙥𝙩𝙪𝙧𝙞𝙣𝙜:
◦ Parentheses () are used to group characters and capture the matched content. For example, (\d{2})/(\d{2})/(\d{4}) captures day, month, and year in a date pattern.𝘼𝙡𝙩𝙚𝙧𝙣𝙖𝙩𝙞𝙤𝙣:
◦ The pipe | symbol is used for alternation, allowing the regex to match either of the patterns. For example, cat|dog matches either "cat" or "dog".𝘾𝙝𝙖𝙧𝙖𝙘𝙩𝙚𝙧 𝙀𝙨𝙘𝙖𝙥𝙚𝙨:
◦ Backslashes followed by certain characters represent special sequences. For example, \d matches any digit, and \s matches any whitespace character.𝘼𝙣𝙘𝙝𝙤𝙧𝙨:
◦ Anchors assert a position in the string. Examples include ^ for the start of the string and $ for the end of the string.𝙒𝙤𝙧𝙙 𝘽𝙤𝙪𝙣𝙙𝙖𝙧𝙞𝙚𝙨:
◦ \b is a word boundary anchor that matches the position between a word character (as defined by \w) and a non-word character.
Top comments (1)
This is an interesting topic, well explained.