Special Characters Meaning and Operators ? 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 (i.e. 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, means VXI|GPIB not (VXI)|(GPIB), VXI(I|G)PIB. (exp) Grouping characters or expressions. RULE 4.4.1 The grouping operator in a regular expression SHALL have the highest precedence. () RULE 4.4.2 The and operators in a regular expression SHALL have the next highest precedence after the grouping + * operator. RULE 4.4.3 The or operator in a regular expression SHALL have the lowest precedence. | Table 4.4.4 Examples Regular Expression Sample Matches GPIB?*INSTR Matches GPIB0::2::INSTR, and GPIB1::1::1::INSTR, GPIB-VXI1::8::INSTR. GPIB[0-9]*::?*INSTR Matches and GPIB0::2::INSTR but not GPIB1::1::1::INSTR GPIB-VXI1::8::INSTR. GPIB[0-9]::?*INSTR Matches and GPIB0::2::INSTR but not GPIB1::1::1::INSTR GPIB12::8::INSTR. Table 4.4.4 Examples (continued) Regular Expression Sample Matches
Special Characters and Operators Meaning ? 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 (i.e. '\?'), 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. RULE 4.4.1 The grouping operator () in a regular expression SHALL have the highest precedence. RULE 4.4.2 The + and * operators in a regular expression SHALL have the next highest precedence after the grouping operator. RULE 4.4.3 The or operator | in a regular expression SHALL have the lowest precedence. Table 4.4.4 Examples Regular Expression Sample Matches GPIB?*INSTR Matches GPIB0::2::INSTR, GPIB1::1::1::INSTR, and GPIB-VXI1::8::INSTR. GPIB[0-9]*::?*INSTR Matches GPIB0::2::INSTR and GPIB1::1::1::INSTR but not GPIB-VXI1::8::INSTR. GPIB[0-9]::?*INSTR Matches GPIB0::2::INSTR and GPIB1::1::1::INSTR but not GPIB12::8::INSTR. Table 4.4.4 Examples (continued) Regular Expression Sample Matches
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