Mikroelektronika MIKROE-350 Fiche De Données

^PORTA

- matches string ' 

PORTA

' only if it's at the beginning of line 

PORTA$

- matches string ' 

PORTA

' only if it's at the end of line 

^PORTA$

- matches string ' 

PORTA

' only if it's the only string in line 

PORT.r

- matches strings like '

PORTA

', '

PORTB

', '

PORT1

' and so on 

The 

"^"

metacharacter by default is only guaranteed to match beginning of the input

string/text, and the 

"$"

metacharacter only at the end. Embedded line separators

will not be matched by 

^"

or 

"$"

. 

You may, however, wish to treat a string as a multi-line buffer, such that the 

"^"

will

match after any line separator within the string, and 

"$"

will match before any line

separator. 
Regular expressions works with line separators as recommended at http://www.uni-
code.org/unicode/reports/tr18/ 

\w

- an alphanumeric character (including "_") 

\W

- a nonalphanumeric character 

\d

- a numeric character 

\D

- a non-numeric character 

\s

- any space (same as

[\t\n\r\f]

) 

\S

- a non space 

You may use 

\w, \d

and

\s

within custom character classes.

routi\de

- matches strings like '

routi1e

', '

routi6e

' and so on, but not 

'

routine

', '

routime

' and so on. 

A word boundary (

"\b"

) is a spot between two characters that has an alphanumer-

ic character (

"\w"

) on one side, and a nonalphanumeric character (

"\W"

) on the

other side (in either order), counting the imaginary characters off the beginning and
end of the string as matching a 

"\W"

. 

\b

- match a word boundary) 

\B

- match a non-(word boundary) 

64

- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 2