Mikroelektronika MIKROE-724 データシート

mikroBasic PRO for dsPIC30/33 and PIC24

MikroElektronika

111

Examples:

count.*r ß

- matches strings like

'counter'

'countelkjdflkj9r'

and

'countr'

count.+r

- matches strings like

'counter'

'countelkjdflkj9r'

but not

'countr'

count.?r

- matches strings like

'counter'

'countar'

and

'countr'

but not

'countelkj9r'

counte{2}r

- matches string

'counteer'

counte{2,}r

- matches strings like

'counteer'

'counteeer'

etc.

counte{2,3}r

- matches strings like

'counteer'

, or

'counteeer'

but not

'counteeeer'

A little explanation about "greediness". "Greedy" takes as many as possible, "non-greedy" takes as few as possible.

For example,

'b+'

and

'b*'

applied to string

'abbbbc'

return

'bbbb'

'b+?'

returns

'b'

'b*?'

returns empty

string,

'b{2,3}?'

returns

'bb'

'b{2,3}'

returns

'bbb'

Metacharacters - Alternatives

You can specify a series of alternatives for a pattern using

"|"

to separate them, so that

bit|bat|bot

will match

any of

"bit"

"bat"

, or

"bot"

in the target string as would

"b(i|a|o)t)"

. The first alternative includes everything

from the last pattern delimiter

("(", "["

, or the beginning of the pattern) up to the first

"|"

, and the last alternative

contains everything from the last

"|"

to the next pattern delimiter. For this reason, it's common practice to include

alternatives in parentheses, to minimize confusion about where they start and end.

Alternatives are tried from left to right, so the first alternative found for which the entire expression matches, is the

one that is chosen. This means that alternatives are not necessarily greedy. For example: when matching

rou|rout

against

"routine"

, only the

"rou"

part will match, as that is the first alternative tried, and it successfully matches the

target string (this might not seem important, but it is important when you are capturing matched text using parentheses.)

Also remember that "|" is interpreted as a literal within square brackets, so if you write

[bit|bat|bot]

, you're really

only matching

[biao|]

Examples:

rou(tine|te)

- matches strings

'routine'

'route'

Metacharacters - Subexpressions

The bracketing construct

( ... )

may also be used for define regular subexpressions. Subexpressions are numbered

based on the left to right order of their opening parenthesis. The first subexpression has number

‘1’

Examples:

(int){8,10}

matches strings which contain 8, 9 or 10 instances of the

‘int’

routi([0-9]|a+)e

matches

‘routi0e’

‘routi1e’

‘routine’

‘routinne’

‘routinnne’

etc.

Metacharacters - Backreferences

Metacharacters

through

are interpreted as backreferences.

matches previously matched subexpression

Examples:

(.)\1+

matches

‘aaaa’

and

‘cc’

(.+)\1+

matches

‘abab’

and

‘123123’

([‘”]?)(\d+)\1

matches

“13”

(in double quotes), or

‘4’

(in single quotes) or

(without quotes) etc.