Regular expressions
The table below describes many of the regular expression characters and how they are used to match the input string.
Groups may be extracted using the group notation in the regular expression. A group is surrounded by parentheses - "(" and ")" in the regular expression. An expression to extract the kind of dog would look like "The (.*) dog". The result has a GROUPS array containing a single element indicating what kind of dog was described in the string.
Characters | Description |
|---|---|
x | The character x |
\\ | The backslash character |
\t | The tab character ( '\u0009') |
\n | The newline (line feed) character ( '\u000A') |
\r | The carriage-return character ( '\u000D') |
\f | The form-feed character ( '\u000C') |
\e | The escape character ( '\u001B') |
Character classes | Description |
|---|---|
[abc] | a, b, or c (simple class) |
[^abc] | Any character except a, b, or c (negation) |
[a-zA-Z] | a through z or A through Z, inclusive (range) |
[a-d[m-p]] | a through d, or m through p: [a-dm-p] (union) |
[a-z&&[def]] | d, e, or f (intersection) |
[a-z&&[^bc]] | a through z, except for b and c: [ad-z] (subtraction) |
[a-z&&[^m-p]] | a through z, and not m through p: [a-lq-z](subtraction) |
Predefined character classes | Description |
|---|---|
. | Any character (may or may not match line terminators) |
\d | A digit: [0-9] |
\D | A non-digit: [^0-9] |
\s | A whitespace character: [\t\n\x0B\f\r] |
\S | A non-whitespace character: [^\s] |
\w | A word character: [a-zA-Z_0-9] |
\W |
Boundary matchers | Description |
|---|---|
^ | The beginning of a line |
$ | The end of a line |
\b | A word boundary |
\B | A non-word boundary |
\A | The beginning of the input |
\G | The end of the previous match |
\Z | The end of the input but for the final terminator, if any |
\z | The end of the input |
Greedy quantifiers | Description |
|---|---|
X ? | X, once or not at all |
X * | X, zero or more times |
X + | X, one or more times |
X { n } | X, exactly n times |
X { n ,} | X, at least n times |
X { n , m } | X, at least n but not more than m times |
Reluctant quantifiers | Description |
|---|---|
X ?? | X, once or not at all |
X *? | X, zero or more times |
X +? | X, one or more times |
X { n }? | X, exactly n times |
X { n ,}? | X, at least n times |
X { n , m }? | X, at least n but not more than m times |
Possessive quantifiers | Description |
|---|---|
X ?+ | X, once or not at all |
X *+ | X, zero or more times |
X ++ | X, one or more times |
X { n }+ | X, exactly n times |
X { n ,}+ | X, at least n times |
X { n , m }+ | X, at least n but not more than m times |
Example:
string1 = "BMC Software"
string2 = "CCS Solution"
result1 = regex(string, "^MVCM$")
// Exact match - result1.MATCHES will be true
if result1.MATCHES == true then
// Do the work here.
endif
result2 = regex(string1, "BMC")
// Partial match
if result2.MATCHES == true then
// Do the work here.
endif
result3 = regex(string2, "^CCS.*")
// Starts with "CCS" with anything after that
if result3.MATCHES == true then
//88
// Do the work here.
endif
string3 = "The lazy dog"
result4 = regex(string3, "The (.*) dog")
if result4.MATCHES == true then
kindofdog = result4.GROUPS[0]
//
endif