The following characters have special functions in regular expressions, so they cannot be used literally (for example, if you had the string s@mple $earch, you could not replace the $ with an s by using regexr("s@mple $earch,"$","s").
[ \ ^ $ . | ? * + ( )
| Character | Description | Example | Notes |
|---|---|---|---|
| Any character | That character | j matches j | |
| \ (backslash) [\^%.|?*+() | Allows you to match special characters | \%
matches % \\ matches \ | accounts for leap seconds |
| \n \r \t | matches a newline, carriage return, or a tab, respectively |
Character Classes are groupings of characters. For example, if you wanted to find words starting with vowels, you would use [aeiou], or words containing the last 5 letters of the alphabet, you would use [w-z]. The special characters inside Character Classes are ^ - ] \. Which means, you cane use $ or parantheses literally.
| [any group of characters] | will match any of the characters within the brackets | [abc] matches a, b, or c | |
| \ (backslash) ^ - ] \ | Allows you to include the special characters | [\^\]] matches ^ or ] | |
| - | denotes a range of characters | [a-z] matches any
letter between a and z [1-5] matches 1, 2, 3, 4, or 5 | |
| ^ | acts as negator: so it will match characters excluded from the Character Class | [^aeiou] matches any consonant |
| . | matches any single character | sh.rt will match shirt or short or sh3rt, etc. | |
| ^ | matches string at beginning expression | ^cat matches cataract, cat, catemarang, etc. | |
| $ | matches string at end of expression | tion$ matches motion, potion, solution, etc. | |
| | | or operator | ca|al matches cat, alligator, camera, etc. | |
| ? | makes preceding item optional | cat? matches catapult, car, cake, etc. | |
| * | repeats the previous item zero or more times | M(iss)*i matches Mississippi, Missing, Milk, etc. | |
| + | repeats the previous item one or more times | M(iss)+i matches Mississippi, Missing, Missive, etc. (not Milk) | |
| {n} | repeats the previous item n times | ||
| {n,} | repeats the previous item at least n times | ||
| {n,m} | repeats the previous item between n and m times | ||