labview的正则表达式语法 来自labview的帮助

Special Characters for Match Regular Expression(

正则表达式

) and Search and

Replace String

Use these special characters in the

regular expression

input of the

Match Regular Expression

and

Search

and Replace String

functions. Right-click the Search and Replace String function and select

Regular

Expression

from the shortcut menu to configure the function for advanced regular expression searches and

partial match substitution in the replacement string.

Resize

the Match Regular Expression function to view

any partial matches found in the string. You can use the

Match Pattern

function or the Match Regular

Expression function to search strings for regular expressions. The Match Regular Expression function gives

you more options for matching strings but performs more slowly than the Match Pattern function.

Note

The Match Regular Expression function does not support null characters in strings. Also, a

pattern can return a successful match of an empty string. If a pattern does not return a successful

match, the

offset past match

will return

–

1.

Regular expression support is provided by the

PCRE library package

. The license under which the PCRE

library package is redistributed can be found on the

Copyright

page at

Important Information?

Copyright

on the

Contents

tab.

Refer to the PCRE Web site at for more information about Perl Compatible Regular

Expressions.

Special

Character

.

Interpreted As

Matches any single character except a newline character. For example, .t matches at, bt, 2t, _t,

and so on.

Marks part of a pattern as one that can appear zero or more times in the input. For example,

be* marks e as a pattern that can appear 0 or more times. Therefore, be* matches be in believe,

bee in beep, and b in bat. In the last example, the e* did not match a character, but the whole

match still succeeded. This can be a problem if the whole pattern is marked with an asterisk.

For example, the pattern b* matches b in baac. The pattern b*, however, also matches an

empty string or abbc, returning a successful match with

whole match

returning an empty

string.

Marks part of a pattern as one that can appear one or more times in the input. For example, be+

matches be in believe, bee in beep, and fails (no match) with bat.

Marks part of a pattern as one that can appear zero or one time in the input. For example, be?

matches be in believe, be in bee, be in beep, and b in bat.

Marks a part of a pattern as one that can appear an arbitrary number of times in a specific

range. For example, be{2} matches b followed by at least two e characters. be{0,3} matches b

followed by at most three e characters. be{2,3} matches b followed by at least two, but at most

three e characters.

Creates character classes, which allow you to match any one of a set of characters. For

example, [abc123] matches the characters a, b, c, 1, 2, or 3.

*

+

?

{ }

[]

-

Specifies a range of characters. For example, [a-z] matches any lowercase letter. [a-zA-Z0-9]

matches any lowercase or uppercase letter or any digit.

You also can use a character class to match any character not in a given set by adding a caret

(^) to the beginning of the class. For example, [^0-9] matches any character that is not a digit.

[^a-zA-Z0-9] matches any character that is not a lowercase or uppercase letter and also not a

digit.

Indicates partial matches. Separate possible matches in a regular expression with a horizontal

bar (|). For example, (cat|dog) catcher matches cat catcher or dog catcher and remembers the

first part of the match (cat or dog) in the first partial match.

You also can use multiple partial matches.

For example, (a|the) (cat|dog) matches a cat, a dog, the cat, or the dog and remembers the first

word (a or the) in the first partial match and the second word (cat or dog) in the second partial

match.

((fire|police)(wo)?man) Smith matches fireman Smith, policeman Smith, firewoman Smith, or

policewoman Smith. partial match 1 is fireman, policeman, firewoman, or policewoman;

partial match 2 is fire or police; and partial match 3 is

because the ? indicates that wo can appear 0 or one times) or wo (indicating a woman).

Indicates multiple possible matches. For example, cat|dog matches cat in catcher or dog in big

dog.

Anchors a match to the beginning of a string. For example, ^dog matches dog in dog catcher

but not the dog.

Anchors a match at the end of a string when used as the last character of a pattern. For

example, dog$$ matches dog in the dog but not dog catcher.

Cancels the interpretation of any special character in this list.

The following escaped expressions have special meanings:

?

( )

|

^

$$

?

?

?

?

?

?

?

b - Represents a word boundary. A word boundary is a character that is not a word

character adjacent to a character that is a word character and vice versa. A word

character is an alphanumeric character or an underscore (_). For example, bhat

matches hat in hatchet but not in that. hatb matches hat in that but not in hatchet.

bhatb matches hat in hat but not in that or hatchet.

c - Matches any control or non-printing character; includes any code point in the

character set that does not represent a written symbol

w - Matches any word character; equivalent to [a-zA-Z0-9_]

W - Matches any non-word character; equivalent to [^a-zA-Z0-9_]

d - Matches any digit character; equivalent to [0-9]

D - Matches any non-digit character; equivalent to [^0-9]

s - Matches any white space character; includes space, newline, tab, carriage return,

and so on

S - Matches any non-white space character