Brian Dunning's FileMaker Custom Functions

FindDuplicateCharacters ( string )

Returns True if the given string

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RealGrouchy   RealGrouchy

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  Sample input:
FindDuplicateCharacters ( "1234561"
  Sample output:

  Function definition: (Copy & paste into FileMaker's Edit Custom Function window)

There are plenty of functions out there to find and manipulate unique or duplicate values within a given list of ΒΆ delimited values, but I couldn't find anything that looked for duplicate *characters* within a string. I whipped this one up.

It's simple enough but I figured I'll upload it for the next person who goes looking for it. It took me more time to look for it than to recreate it because I assumed there *must* be one out there! There probably is one and I just didn't use the right search terms.

- RG>



esc   esc, tokyo
Jun 11, 2018
would be better if

now this function get into infinite loop if parameter is shorter than 1 character (then get ? as result).
RealGrouchy   RealGrouchy
Jun 11, 2018
Good catch. I've submitted the change!

- RG>
Tom Hays   Tom Hays, Virgina, USA
Aug 17, 2018
If the characters in the string are limited to a specific range/set of characters that you can specify explicitly, e.g. 0-9a-zA-Z, then you can write this in a closed form without needing recursion.

alphanum = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
Length(Filter(alphanum; string)) <> Length(string)


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Note: these functions are not guaranteed or supported by Please contact the individual developer with any questions or problems.

Under construction. Email me your wish list for improvements.