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$EXTRACT

M[UMPS] by Example

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Introduced in the 1977 ANSI M[UMPS] language standard.

This function returns substrings of strings that are specified as parameters.

Reference   Value
$Extract("ABCDEFG",2)   "B".
$Extract("ABCDEGF",2,5)   "BCDE"

Assume that X="ABCDEF12345GHI".

Reference   Value
$Extract(X,20)   empty string
$Extract(X,10,99)   "45GHI"
$Extract("",2,3)   empty string

Assume that X="12345619481021MIN123a" and contains a ‘fixed length’ data record:

Registration-number

Reference   Value
$Extract(X,1,6)   123456

Birth date

Reference   Value
$Extract(X,7,14)   19481021

Gender

Reference   Value
$Extract(X,15)   "M"

Department

Reference   Value
$Extract(X,16,17)   "IN"

Room-number

Reference   Value
$Extract(X,18,21)   "123a"

Set X="ABCDE"

Reference   Value
$Extract(X,1)   "A"
$Extract(X,2)   "B"
$Extract(X,1,2)   "AB"
$Extract(X,1,4)   "ABCD"
$Extract(X,0,100)   "ABCDE"
$Extract(X,1.92)   "A"
$Extract(X,99)   ""
$Extract(X,–3)   ""
$Extract(X,3,2)   ""

Set A(1)="2BC"

Reference   Value
$Extract(A(1),A(1))   "B"

Set X="98765"
In the examples below, the open square character (⋥) is displayed where the resulting strings contain spaces, so that the number if space-characters becomes visible.

Reference   Value
Set Y=$Extract(X,3,7)   Y="765"
Set Y=Y_"⋥⋥⋥⋥⋥"   Y="765⋥⋥⋥⋥⋥"
Set Y=$Extract(Y,1,5)   Y="765⋥⋥"

or, in one formula:

Set Y=$Extract($Extract(X,3,7)_"⋥⋥⋥⋥⋥",1,5)

Addition in the 1995 ANSI M[UMPS] Language Standard:

It is allowed to specify a reference to $Extract on the left hand side of the equal sign in a Set command.

Set X="ABCDEFG"

Reference   Value
Set $Extract(X,3)="a"   X="ABaDEFG"
Set $Extract(X,2)="xxx"   X="AxxxaDEFG"
Set $Extract(X,2,6)=""   X="AEFG"

Set X="ABCDEFG"

Reference   Value
Set $Extract(X,2,3)="PQ"   X="APQDEFG"
Set $Extract(X,2,6)="="   X="A=G"
Set $Extract(X,11,12)="PQ"   X="A=G⋥⋥⋥⋥⋥⋥⋥PQ"
Set $Extract(X,2)="PQ"   X="APQG⋥⋥⋥⋥⋥⋥⋥PQ"
Set $Extract(X)="ZzZ"   X="ZzZPQG⋥⋥⋥⋥⋥⋥⋥PQ"

Examples with naked references:

$Extract(VALUE)
Set ^ABC(1,2)="reset naked indicator"
; naked indicator is now ^ABC(1,
Set ^(3,4)=$Extract(^(5,6))
; 1. fetch ^(5,6) = ^ABC(1,5,6)
; 2. store ^(3,4) = ^ABC(1,5,3,4)
; naked indicator is now: ^ABC(1,5,3,

$Extract(VALUE,CHAR)
Set ^ABC(1,2)="reset naked indicator"
; naked indicator is now ^ABC(1,
Set ^(3,4)=$Extract(^(5,6),^(7,8))
; 1. fetch ^(5,6) = ^ABC(1,5,6)
; 2. fetch ^(7,8) = ^ABC(1,5,7,8)
; 3. store ^(3,4) = ^ABC(1,5,7,3,4)
; naked indicator is now: ^ABC(1,5,7,3,

$Extract(VALUE,FROM,TO)
Set ^ABC(1,2)="reset naked indicator"
; naked indicator is now ^ABC(1,
Set ^(3,4)=$Extract(^(5,6),^(7,8),^(9,10))
; 1. fetch ^(5,6) = ^ABC(1,5,6)
; 2. fetch ^(7,8) = ^ABC(1,5,7,8)
; 3. fetch ^(9,10) = ^ABC(1,5,7,9,10)
; 4. store ^(3,4) = ^ABC(1,5,7,9,3,4)
; naked indicator is now: ^ABC(1,5,7,9,3,

Set $Extract(VALUE,FROM,TO)=VALUE
Set ^ABC(1,2)="reset naked indicator"
; naked indicator is now ^ABC(1,
Set $Extract(^(3,4),^(5,6),^(7,8))=^(9,10)
; 1. fetch ^(5,6) = ^ABC(1,5,6)
; 2. fetch ^(7,8) = ^ABC(1,5,7,8)
; 3. fetch ^(9,10) = ^ABC(1,5,7,9,10)
; 4: if ^ABC(1,5,7,8) < ^ABC(1,5,6) or if ^ABC(1,5,7,8) < 1
; don’t store, naked indicator is ^ABC(1,5,7,9,
; else continue
; 5. fetch/store ^(3,4) = ^ABC(1,5,7,9,3,4)
; naked indicator is now: ^ABC(1,5,7,9,3,

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Copyright © Standard Documents; 1977-2024 MUMPS Development Committee;
Copyright © Examples: 1995-2024 Ed de Moel;
Copyright © Annotations: 2003-2008 Jacquard Systems Research
Copyright © Annotations: 2008-2024 Ed de Moel.

The information in this page is NOT authoritative and subject to be modified at any moment.
Please consult the appropriate (draft) language standard for an authoritative definition.

Some specifications are "approved for inclusion in a future standard". Note that the MUMPS Development Committee cannot guarantee that such future standards will indeed be published.

This page most recently updated on 15-Nov-2023, 13:08:30.

For comments, contact Ed de Moel (demoel@jacquardsystems.com)