Backwards ( _Field )

return a string backwards (mirror writing)

Average rating: 4.4 (31 votes) Log in to vote

Alexander Baier - Show more from this author
datamat Software Development
http://fm-tutorial.de

Sample input:

Backwards ( "Hello" )

Backwards ( "12345" )

Sample output:

olleH

54321

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

If ( Length (_Field ) > 0 ;

Backwards ( Right ( _Field ; Length ( _Field ) - 1 ) ) & Left (_Field ; 1 ) ; 

Left ( _Field ; 1 )

)

This recursive function returns any string backwards.

Comments

		Bart, Vero Beach May 23, 2013
I guess this CF begs the question, "why?" Just curious. :-)

		Alexander Baier, datamat Software Development May 23, 2013
- Calculations of checksums - mathematical operations or mathematical curiosities e.g ( 731 - 137 = 594 + 495 = 1089 this algorithm is valid for three-digit numbers (n>m>p)) or simply for mischief :-)

		Daniele Raybaudi, ACI May 27, 2013
concise mode: If ( Length ( _Field ) ; Backwards ( Right ( _Field ; Length ( _Field ) - 1 ) ) ) & Left ( _Field ; 1 )

		John Segers Jun 10, 2015
Beautiful function very usefull to me. I am not at all stupid, but I could never make this one myself. Can somone please explain to me why it's working? THX a lot

		Justin, Salem, Oregon Jun 17, 2015
Just found this function and it was exactly what I was looking for. As far as 'why'? It worked wonders for my need to reverse a string of characters so that I could feed that into the Code() function (which reverses the characters itself in its output). I needed those code points to be in the proper word order, not the reversed Code() output order. It works by passing in an ever diminishing right-hand list of characters to itself, and then returns the left hand side of things once it reaches the end. So say we called Backwards ("abc"). 1) Backwards ("abc") => _field = "abc" 1A) Length > 0, so call Backwards ("bc") & "a" 2) Backwards ("bc") => _field = "bc" 2A) Length > 0, so call Backwards ("c") & "b" 3) Backwards ("c") => _field = "c" 3A) Length > 0, so call Backwards ("") & "c" 4) Backwards ("") => _field = "" 4A) Length NOT >0, so return Left("") (which is empty) 4A returns ("") to 3A => "" & "c" = "c" ...which returns "c" to 2A => "c" & "b" = "cb" ...which returns "cb" to 1A => "cb" & "a" = "cba" I think the calculation could be modified a bit, but haven't tested anything. It works as it is. It isn't Tail recursion, so you wouldn't want to pass strings longer than 10,000 characters to it.

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