regrex package
https://golang.org/pkg/regexp/
On-line Regular Expression
Meta Characters
Metacharacters are characters that are interpreted in a special way by a RegEx engine. Here’s a list of metacharacters:
[] . ^ $ * + ? {} () \ |
[]
– Square brackets
Square brackets specifies a set of characters you wish to match.
.
– Period
A period matches any single character (except newline '\n'
).
– Caret
The caret symbol ^
is used to check if a string starts with a certain character.
$
– Dollar
The dollar symbol $
is used to check if a string ends with a certain character.
*
– Star
The star symbol *
matches zero or more occurrences of the pattern left to it.
+
– Plus
The plus symbol +
matches one or more occurrences of the pattern left to it.
?
– Question Mark
The question mark symbol ?
matches zero or one occurrence of the pattern left to it.
{}
– Braces
Consider this code: {n,m}
. This means at least n, and at most m repetitions of the pattern left to it.
|
– Alternation
Vertical bar |
is used for alternation (or
operator).
()
– Group
Parentheses ()
is used to group sub-patterns.
\
– Backslash
Backlash \
is used to escape various characters including all metacharacters.
Special Sequences
Special sequences make commonly used patterns easier to write.