Sin Categoría | Johan de Bruin

Math	Pattern	Pattern meaning
$Latex \emptyset$	no equivalent
$Latex \epsilon$	no character at all	matches `""`
`c`	`c`	matches `"c"`
$L_1 \circ L_2$	p1p2	matches p1 then p2
$L_1 \cup L_2$	p1`\|`p2	matches p1 or p2
$L^\star$	p`*`	matches `""` or p repeated
$L^+$	p`+`	matches p repeated, but not `""`
$L^?$	p`?`	matches p or `""`
$L^n$	p`{n}`	matches p repeated n times
$L^{[n,m]}$	p`{n,m}`	matches p repeated n to m times
$Latex \Sigma$	`.`	matches any character
$Latex \{c_1,\ldots,c_n\}$	`[c₁...c_n]`	matches $c_1$ or $c_2$ or … or $c_n$
$Latex \Sigma - \{c_1,\ldots,c_n\}$	`[^c₁...c_n]`	matches any char but $c_1$ or … or $c_n$
$(L)$	`(`p`)`	matches p, remembers submatch
no equivalent	`\`n	matches string from nth submatch
no equivalent	`\b`	matches a word boundary
no equivalent	`\w`	matches a word character, e.g., alphanumeric
no equivalent	`\W`	matches a nonword character, e.g., punctuation
no equivalent	`\s`	matches a whitespace character, e.g., space, tab, return
no equivalent	`\S`	matches a non-whitespace character, e.g., alphanumeric, punctuation
no equivalent	`\d`	matches a digit character, i.e., 0-9
no equivalent	`\D`	matches a non-digit character, e.g., alphanumeric, punctuation
no equivalent	`^`	matches start of line/string
no equivalent	`$`	matches end of line/string
no equivalent	`[c₁-c₂]`	matches $c_1$ through $c_2$