There are special characters for creating almost any pattern.
Special Pattern Matching Characters
CharacterDescription
\wMatches any word character (alphanumeric).
\WMatches any non-word character.
\sMatches any whitespace character (tab, newline, carriage return, form feed, vertical tab).
\SMatches any non-whitespace character.
\dMatches any numerical digit.
\DMatches any character that is not a number.
[\b]Matches a backspace.
.Matches any character except a newline.
[...]Matches any one character within the brackets.
[^...]Matches any one character not within the brackets.
[x-y]Matches any character in the range of x to y.
[^x-y]Matches any character not in the range of x to y.
{x,y}Matches the previous item at least x times but not to exceed y times.
{x,}Matches the previous item at least x times.
{x}Matches the previous item exactly x times.
?Matches the previous item once or not at all.
+Matches the previous item at least once.
*Matches the previous item any number of times or not at all.
|Matches the expression to the left or the right of the | character.
(...)Group everything inside parentheses into a subpattern.
\xMatches the same characters that resulted from the subpattern in group number x. Groups, which are designated with parentheses, are numbered from left to right.
^Matches the beginning of the string or beginning of a line, in multiline matches.
$Matches the end of the string or end of a line, in multiline matches.
\bMatches the position between a word character and a non-word character.
\BMatches the position that is not between a word character and a non-word character.