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 FileMaker Pro Custom Functions

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ConvertFractToNum ( number )

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  Average rating: 4.5  (32 votes)
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Colin Keefe, IT Solutions Consulting, Inc

Converts a fraction to a real number.

Sample Input:
ConvertFractToNum(5 1/2)
Sample Output:

 Then copy & paste into FileMaker Advanced's Edit Custom Function window.


I've been using Mikhail Edoshin's Fraction() custom function for awhile now - it's great. (see:

For a particular application, I needed a method to convert user-entered fractions back into a real number, so I could perform math on it, so I wrote this up to complement Mikhail's function. Feed it a fraction, and it'll do its level best to produce a real number.

There's some room for improvement here in terms of error capture, but much of that could be handled at field-level validation, to prevent malformed fractions from being entered.

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

This is my Custom Function and I want to edit it


This is handy, but doesn't correctly handle fractions without a space (e.g. "1/2"). I've modified it a bit:

Let ( [
$number = Trim(number);
$integer = LeftWords($number;1);
$denominator = Right ( $number ; Length($number)-Position($number; "/";1;1 ));
$numerator = Middle ( $number ; Position ( $number ; " "; 1 ; 1 ) ; Position ( $number ; "/"; 1 ; 1 )-Position ( $number ; " "; 1 ; 1 ) )

// no slash, so no fraction

// no space, so no valid fraction
PatternCount($number;" ")=0;$numerator/$denominator;

// too many spaces, so no valid fraction
PatternCount($number;" ")>1;$number;

// - we have a fraction to parse
$integer + ($numerator/$denominator)

Sam Barnum, 360Works
November 16, 2010 11:48am

Is there a way to use this with negative fractions? Say I have -2 4/8
right now it returns 2.5 when i would like it to return -2.5

Any help would be appreciated.


Matt, Calgary
August 16, 2012 10:14pm

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Answer 6 + 5 =
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