User`s guide

Programming with VISA 3
Agilent VISA User’s Guide 49
grouping operator, and the or operator | in a regular
expression has the lowest precedence. The following table
provides detailed descriptions of special characters and
operators. Some example expressions follow in Table 14.
Table 13 Descriptions of Special Characters and Operators
Special
Characters and
Operators
Description
? Matches any one character.
\ Makes the character that follows it an ordinary character
instead of special character. For example, when a question
mark follows a backslash (e.g.,’ '\?’), it matches the '?'
character instead of any one character.
[list] Matches any one character from the enclosed list. A hyphen
can be used to match a range of characters.
[^list] Matches any character not in the enclosed list. A hyphen
can be used to match a range of characters.
* Matches 0 or more occurrences of the preceding character
or expression.
+ Matches 1 or more occurrences of the preceding character
or expression.
exp|exp Matches either the preceding or following expression. The
or operator | matches the entire expression that precedes
or follows it and not just the character that precedes or
follows it. For example, VXI|GPIB means (VXI) | (GPIB),
not VXI(I|G)PIB.
(exp) Grouping characters or expressions.
“ “ Sends a blank space.
\n Sends the ASCII line feed character. The END identifier will
also be sent.
\r Sends an ASCII carriage return character.
\t Sends an ASCII TAB character.
\### Sends ASCII character specified by octal value.