Explaination about Shorthand character sets.mp4

Download Explanation about Regex shortnand character sets.mp4

 Here’s a simple and clear explanation of the most common Regex shorthand character sets, with easy examples to help you understand how they work.

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✅ Regex Shorthand Character Sets (Explained Simply)

Regular expressions (regex) use shorthand character sets to make pattern-matching easier.
Instead of writing long character ranges, you can use short symbols like \d, \w, \s, etc.

Below is a friendly explanation of each.

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🔹 1. \d → Digit characters

Meaning: Matches any number from 0–9

Examples:

• Regex: \d
  Matches: 3 in "A3Z"

• Regex: \d\d
  Matches: "45" in "Age: 45"

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🔹 2. \D → Non-digit characters

Meaning: Matches anything except 0–9

Examples:

• Regex: \D
  Matches: A in "A3"

• Regex: \D+
  Matches: "Name" in "Name123"

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🔹 3. \w → Word characters

Meaning: Matches

• Letters (A–Z, a–z)

• Numbers (0–9)

• Underscore (_)

Examples:

• Regex: \w
  Matches: a in "a!"

• Regex: \w+
  Matches: "Hello123" in "Hello123!!"

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🔹 4. \W → Non-word characters

Meaning: Matches anything except letters, numbers, and underscore

Examples:

• Regex: \W
  Matches: ! in "Hi!"

• Regex: \W+
  Matches: " @#" in "User @# Name"

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🔹 5. \s → Whitespace characters

Meaning: Matches spaces, tabs, and newlines
(space, \t, \n)

Examples:

• Regex: \s
  Matches the space in "Hello World"

• Regex: \s+
  Matches " " (multiple spaces)

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🔹 6. \S → Non-whitespace characters

Meaning: Matches anything that is not space, tab, or newline

Examples:

• Regex: \S
  Matches: H in " Hello"

• Regex: \S+
  Matches: "Hello" in "Hello World"

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📌 Additional Character Class Shorthands (POSIX Style)

Some regex engines (like Linux grep -E, PHP, Perl) use POSIX character classes inside [[: ... :]].

Examples:

🔹 [:digit:] → Digits (0–9)

🔹 [:alpha:] → Alphabet letters (A–Z, a–z)

🔹 [:alnum:] → Letters + numbers

🔹 [:upper:] → Uppercase letters

🔹 [:lower:] → Lowercase letters

Example use:

[[:digit:]]+

Matches "2024" in "Year: 2024"

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🎯 Summary Table (Quick View)

Shorthand	Meaning	Example Match
\d	Digit	5
\D	Not a digit	A
\w	Word character	A, 3, _
\W	Not word character	!
\s	Whitespace	(space)
\S	Non-whitespace	H
[[:digit:]]	Digit	7
[[:alpha:]]	Letters	A, z

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