Character Escapes

Character escapes act as shorthands for some common character classes.

Digit character — \d

The character escape \d matches digit characters, from 0 to 9. It is equivalent to the character class [0-9].

\D is the negation of \d and is equivalent to [^0-9].

Word character — \w

The escape \w matches characters deemed “word characters”. These include:

• lowercase alphabet — a–z
• uppercase alphabet — A–Z
• digits — 0–9
• underscore — _

It is thus equivalent to the character class [a-zA-Z0-9_].

Whitespace character — \s

The escape \s matches whitespace characters. The exact set of characters matched is dependent on the regex engine, but most include at least:

• space
• tab — \t
• carriage return — \r
• new line — \n
• form feed — \f

Many also include vertical tabs (\v). Unicode-aware engines usually match all characters in the separator category.

The technicalities, however, will usually not be important.

Any character — .

While not a typical character escape, . matches any¹ character.