G.3 Comparison between types of regular expressions

String

Matches lines containing the specified string.

Y

Y

Y

Y

^string

Matches the specified string at the beginning of a line.

Y

Y

Y

Y

string$

Matches the specified string at the end of a line.

Y

Y

Y

Y

^string$

Combination of ^ and $. Matches lines containing only the specified string.

Y

Y

Y

Y

^$

Combination of ^ and $. Matches empty lines.

Y

Y

Y

Y

. (period)

Matches any single character.

Y

Y

Y

Y

char*

Matches strings of zero or more occurrences of the preceding character.

Y

Y

Y

Y

.*

Combination of a period (.) and asterisk (*). Matches any character string.

Y

Y

Y

Y

char+

Matches strings of one or more occurrences of the preceding character.

N

Y

N

Y

char?

Matches strings of zero or one occurrence of the preceding character.

N

Y

N

Y

regex|regex

Matches either regular expression.

N

Y

N

Y

(regex)

Groups a regular expression. Used to explicitly indicate to the program that the specified characters are a regular expression. Used mainly with a vertical bar (|). (See G.4 Tips on using regular expressions.)

N

Y

N

Y

char{n}

Matches strings in which the preceding character occurs n times.

N

Y

N

Y

char{n,}

Matches strings in which the preceding character occurs at least n times.

N

Y

N

Y

char{n,m}

Matches strings in which the preceding character occurs at least n times but no more than m times.

N

Y

N

Y

[string]

Matches any character specified in the string enclosed in square brackets.

N

Y

Y

Y

[^string]

Matches any character not specified in the string enclosed in square brackets.

N

Y

Y

Y

[char-char]

Matches any character in the range, in ascending order of the character codes.

N

Y

Y

Y

[^char-char]

Matches any character not in the specified range, in ascending order of the character codes.

N

Y

Y

Y

\special-char

Handles the special character as an ordinary character.

Y

Y

Y

Y