String Manipulation Functions

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The functions in this section are used primarily to manipulate strings. Since the Media Center expression language is primarily string-oriented, these functions provide a means to manipulate field values or the output from other expressions.


Clean a string to be used for various operations.
Description clean(string, mode)

The Clean() function is generally used to sanitize a string by stripping empty brackets, remove superfluous dash characters, eliminate leading or trailing articles, or replace filesystem-illegal characters. It is typically employed before some operation such as Rename to clean the product of joining various fields, some of which may be empty, or to produce filesystem-safe filenames. It may be used for a variety of purposes, however.

Available mode values:

0Removes empty () and [], superfluous dash (-) and whitespace characters and sometimes comma (be careful)
1Removes the article 'the' from the beginning and ', the' from the end
2Removes any article (a, an, the, etc.) from the beginning and end
3Replaces each filesystem-illegal character \ / : * ? " < > | with an underscore _, and replaces each unprintable character with a space

Argument mode is optional (defaults to 0).

Examples clean([album] - [date])

The concatenation of [Album] - [Date] may leave a dangling - string when date is empty. Clean() in the default mode removes this dangling string.

clean(The Beatles, 1)

For sorting or grouping purposes, it is often desirable to remove the leading article The from a string. Clean() in mode 1 provides a convenient solution, and in this example produces Beatles.

clean(AC//DC: Back In Black, 3)

When an expression is to be used to produce a filename, filesystem-illegal characters must be removed or converted to legal characters. Clean() in mode 3 will convert such characters into safe underscores. This example would produce the filesystem-safe value of AC_DC_ Back In Black.

clean(\//:*?"<>|, 3)

This trivial example demonstrates how all filesystem-illegal characters are converted to underscores, producing the nine-character output _________ which consists entirely of underscores.


Changes the case of a given string.
Description fixcase(string, mode)

The FixCase() function will convert the supplied text string according to the specified mode.

Available mode values:

0Title Case
1All Words
2First Word
3All Uppercase
4All Lowercase
5All Words (preserve existing capitalization)

Argument mode is optional (defaults to 0).

Examples fixcase(enjoy the silence)

The default mode 0 is used, so the output is Enjoy the Silence.

fixcase(enjoy the silence, 1)

Using mode 1, all words are uppercased, so the output is Enjoy The Silence.

fixcase(MY ALbUm IS cAlLeD: adam, 4)

Outputs my album is called: adam.


Intelligently splits adjacent camel-cased words.
Description fixspacing(string, mode)

The FixSpacing() function inserts spaces between adjacent camel-cased words in string. It is useful for helping to clean and convert metadata that favors compactness over standard sentence structure.

Available mode values:

0Disables conversion
1Enables camel-case conversion

Argument mode is optional (defaults to 1).

Examples fixspacing(OneWorld)

Outputs One World.

fixspacing([name], 1)

Outputs the name field with any camel-case converted into standard sentence structure. If the value of name was, MiracleOn34thStreet, the output would be Miracle On 34th Street.

fixspacing(Another [name])

Assuming the same [name] as above, this would return Another Miracle On 34th Street.


Hexifies a string to make it suitable for web usage.
Description hexify(string)

The Hexify() function URI encodes a string to make it useable by a browser or search engine. Hexify() is typically used by expressions generating or working on URLs in Media Center's Link Manager.

Examples hexify(Oasis - /(What's The Story/) Morning Glory?)

The result is Oasis%20-%20%28What%27s%20The%20Story%29%20Morning%20Glory%3F.


Retrieves a specified number of characters from the left of a string.
Description left(string, quantity)

The Left() function retrieves no more than quantity characters from the left of the string.

Examples left([filename], 3)

Return the Windows drive letter, colon and first back-slash from the filename.


Returns the number of characters in a string.
Description length(string)

The Length() function returns the number of characters contained in string.

Examples length(A Simple Plan)

Returns 13.

if(compare(length([filename]), >=, 68), Long, Short)

The length of the filename is calculated, and compared against 68, outputting Long when the length is greater than or equal to 68, and Short otherwise.


Retrieves specified characters from a string.
Description mid(string, start position, quantity)

The Mid() function returns a specified quantity of characters from the start position in string.

The start position is 0-based (i.e. the first character is considered position 0). A quantify of -1 returns all characters from the start positionning to the end of string.

Argument start position is optional (defaults to 0).

Argument quantity is optional (defaults to 1).

Examples mid(12345)

Returns 1, using is the default quantity (1) of characters from the default start position of (0 - the beginning of the string).

mid(12345, 1, 2)

Returns 2 characters beginning at start position 1, which is 23.

Additional Examples

An example that uses Mid() to re-order a date field.
An example that uses Mid() to output a number of stars based on an arbitrary rating value.


Regular expression pattern matching and capture.
Description regex(string, regexp, run mode, case sensitivity)

The Regex() function performs regular expression (RE) pattern matching on a string. The string is evaluated against the regular expression regexp, and run mode dictates the values output by Regex(). The three modes allow for match testing, capture output, or silent operation.

All match captures are placed into special variables referenced as [R1], [R2], ... [R9], which can be used in later in the expression. The contents of the captures [R1] ... [R9] are available until the end of the expression, or Regex() is run again, whereby they are replaced. The regular expression implementation used prior to Media Center 19 is the Microsoft 2010 TR1 engine, and in Media Center 19 it is the Boost engine. Additional information is available regarding the full syntax and other implementation details.

Available run mode values:

0Runs in Boolean test mode, returning either a 1 or 0, indicating whether the string matched (1) or did not match (0) the regexp. This run mode is useful within an If() test, so that different true or false actions may be taken.
1 to 9Outputs the specified Nth capture group's contents, where N ranges from 1 to 9. Only a single capture is output in this mode, but all captures are available in the [R1] ... [R9] capture variables. This run mode is used to easily output a single matching sub-string.
-1Runs in silent mode, with no output being produced. This run mode is useful as a means to capture portions of the string to be later used in subsequent portions of an expression.

The case sensitivity argument toggles the case-sensitivity of regular expression matching. Note that case insensitivity does not apply to characters inside a character class [ ]. Use both uppercase and lowercase characters when necessary to match either case (e.g. [aAbB] to match either uppercase or lowercase A or B).

Available case sensitivity values:

0Ignore case when matching (e.g. the letters E and e are identical)
1Consider case when matching (e.g. the letters E and e are considered different)

The regular expression language assigns special meaning to many characters. A few of these meta-characters, such as forward slash /, comma , and both ( and ) are also reserved and used by the Media Center expression language. To force the Media Center expression engine to ignore the meta-characters in regexp, surround the entire regular expression with /# #/. This is one of Media Center's escapements, which tells the expression engine to ignore everything inside, so that the entire, uninterpreted regexp can be provided to the Regex() regular expression evaluator. Although surrounding regexp by /# #/ is not necessary or required when no conflicting characters are in use, and you may manually escape the expression languages meta-characters with a forward slash /, it is probably a safe practice to always encase every regexp within /# #/.

Argument run mode is optional (defaults to 0).

Argument case sensitivity is optional (defaults to 0).

Examples ifelse(regex([name], /#^(the|an|a)\b#/, 0, 1), Fix your case!)

Searches the name field for any of the lowercase articles the, and and a at the beginning of name, and outputs Fix your case! when the match succeeds. The run mode is 0 which is a test and capture mode, and case sensitivity is enabled.

if(regex([artist], /#([[:punct:]])#/, 0), [R1] --> [Artist], No Punctuation)

Using the default mode 0, Regex() will output a Boolean for use inside a conditional to cause some action to occur based on the match success or failure. This example matches against the artist field looking for any punctuation character. If the match succeeds (a punctuation character was found), that character is output followed by the string --> and the artist. In there was no match, the string No Punctuation is output.

regex(D03T02 some track.mp3, /#^D(\d+)T(\d+)#/, 1)Disc: [R1], Track: [R2]

The string is matched against the regexp that is looking for a D followed by any number of digits, followed by a T and then more digits. Those digits were captured, and later used to output the value Disc: 03, Track: 02.

regex([filename (name)], /#^(\d+)-#/, -1)Track number is [R1]

Using run mode -1, the file's name is pattern tested against the regexp which is looking for leading digits followed by a dash. Those digits are captured in buffer [R1] which is used later in the expression. If the file name was 2-foo.mp3, the output would be Track number is 2.

regex([filename], /#(\d{1,2})\.(\d{1,2}).(\d{4})#/, -1)[R3]//[R1]//[R2]

Matches and captures a date formatted as anywhere within the filename, and rearranges it in a standard format of yyyy/mm/dd. Since run mode is -1, no output occurs. However, captured match segments are made available for subsequent use. The three captures, [R1], [R2] and [R3] are arranged in the textual output so that we get the desired year/month/day ordering, such as 2011/08/19.


Removes a list of characters from a string.
Description removecharacters(string, character list, mode)

The RemoveCharacters() function will remove from string any characters in the character list. The characters removed depend upon the mode specified. The function operates in a case-sensitive manner.

Available mode values:

0Remove all instances
1Remove from the beginning only
2Remove from the end only
3Remove from each end

Argument mode is optional (defaults to 0).

Examples removecharacters(Paper, Ppr)

Removes P, p, and r from Paper, resulting in ae. The default mode 0 is in effect, removing all instances of the characters specified in the character list.

removecharacters(Paper, Ppr, 1)

With mode 1 set, only the initial character P is removed, resulting in aper.

removecharacters(Paper, Ppr, 2)

In mode 2, only one character from the end of the string are removed, leaving "Pape.

removecharacters(Paper, Ppr, 3)

Both the front and back are affected in mode 3, causing the removal of the leading P and trailing r resulting in ape.

removecharacters([artist], /(/))

Removes any ( and ) characters from anywhere within the [artist] field.


Trims characters from the beginning of a string.
Description removeleft(string, quantity)

The RemoveLeft() function removes a specified quantity of characters from the left side of a string. If the quantity is larger than the length of the string, the output will be empty.

Examples removeleft(Good Deeds, 5)

Removes the first 5 characters from resulting in Deeds being output.


Trims characters from the end of a string====
Description removeright(string, quantity)

The RemoveRight() function removes a specified quantity of characters from the right side of a string. If the quantity is larger than the length of the string, the output will be empty.

Examples removeright(03-02-1959,5)

Removes the last 5 characters from the given date, leaving only the month and year 03-02.


Replace or remove a string segment====
Description replace(string, old, new)

The Replace() function replaces all instances of old within string with new. If new is unspecified, it defaults to an empty value, causing old to be removed. Replace() operates in a case-sensitive manner.

Argument new is optional (defaults to EMPTY).

Examples replace(The Daily Show with John Oliver, hn Oliver, n Stewart)

Now that John Oliver has completed his summer stand-in for Jon Stewart, it is time for a replacement. The old sequence hn Oliver will be replaced with the new sequence n Stewart, resulting in The Daily Show with Jon Stewart.

replace(Sample String, s, Replaced)

In this example, the original string does not contain the old value s anywhere, so no replacement occurs and the original string is returned.

replace(Led Zeppelin.[remastered], .[remastered])

Removes the trailing old value .[remastered] from the original string, resulting in Led Zeppelin. Because no new string is specified, the default empty value is used as a replacement, effectively stripping the old value.


Retrieves a specified number of characters from the right of a string.
Examples right([filename], 3)

Returns the last three characters from the filename (typically this is the file's suffix).


Takes Firstname Lastname and swaps to Lastname, Firstname.
Description swap(string)

The Swap() function is used to reverse the order of a personal name in a string (converting Firstname Lastname into Lastname, Firstname). The function has special handling for strings that end with Jr., Sr., I, II, III, IV, V (so that these common suffixes are handled properly).

Examples swap(Paul Simon)

Reverses the lexical order of the name to Simon, Paul.

swap(Sammy Davis Jr.)

Handles most common name suffixes and results in Davis, Sammy Jr..


Takes Lastname, Firstname and reverses it to Firstname Lastname.

Description unswap(string)

The Unswap() function is the opposite of the Swap() function. It is used to restore the normal western-style order of a personal name in a string (converting Lastname, Firstname into Firstname Lastname).

Examples Unswap(Simon, Paul)

Reverses the lexical order of the name to Paul Simon.