# Regular Expression Patterns

Regular expressions are strings which can be used to find patterns (or lack thereof) in data. Any string can be converted to a regular expression using the .r method.

import scala.util.matching.Regex

val numberPattern: Regex = "[0-9]".r

case None => println("Password must contain a number")
}


In the above example, the numberPattern is a Regex (regular expression) which we use to make sure a password contains a number.

You can also search for groups of regular expressions using parentheses.

import scala.util.matching.Regex

val keyValPattern: Regex = "([0-9a-zA-Z- ]+): ([0-9a-zA-Z-#()/. ]+)".r

val input: String =
"""background-color: #A03300;
|background-position: top center;
|background-repeat: repeat-x;
|background-size: 2160px 108px;
|margin: 0;
|height: 108px;
|width: 100%;""".stripMargin

for (patternMatch <- keyValPattern.findAllMatchIn(input))
println(s"key: ${patternMatch.group(1)} value:${patternMatch.group(2)}")


Here we parse out the keys and values of a String. Each match has a group of sub-matches. Here is the output:

key: background-color value: #A03300
key: width value: 100