2.4.13 EVALUATE

Format:

       EVALUATE {Datenfeld1 / TRUE / FALSE}
       [
        ALSO {Datenfeld2 / TRUE / FALSE}
        ...
       ]


       [
        WHEN { 
               ANY / Bedingung1 / TRUE / FALSE /
               [NOT] Datenfeld3 [ {THRU / THROUGH } Datenfeld4 
             }               
         
        [
         ALSO { 
                ANY / Bedingung2 / TRUE / FALSE /
                [NOT] Datenfeld5 [ {THRU / THROUGH } Datenfeld6 
              }               
         ....
        ]


        Befehlssequenz 1


        [WHEN OTHER Befehlssequenz 2]


       ...
       ]


       [END-EVALUATE]

Mit EVALUATE können Feldinhalte auf unterschiedliche Werte oder Bedingungen untersucht werden.

Ausdruck entspricht einer IF-Abfrage

1. Direkter Wertevergleich

Beispiel:


       identification division.
       environment division.
       data division.
       working-storage section.
       01 numfeld      pic 99.
       procedure division.


        move 9 to numfeld.
        perform check varying numfeld from 9 by 1 until numfeld = 21.
        call getchar.
        stop run.


       check section.
        display numfeld ' ' with no advancving.
        evaluate numfeld       
        when 10             display 'numfeld ist 10'
        when 20             display 'numfeld ist 20'       
        when 11 thru 15     display 'numfeld liegt zwischen 11 und 15'
        when 16 thru 19     display 'numfeld liegt zwischen 16 und 19'
        when other          display 'numfeld ist < 10 oder > 20'
        end-evaluate

2. Bedingungen abfragen

Beispiel:


       identification division.
       environment division.
       data division.
       working-storage section.
       01 numfeld      pic 99.
       procedure division.


        perform check varying numfeld from 9 by 1 until numfeld = 16.
        call getchar.
        stop run.


       check section.
        display numfeld ' ' with no advancving.
        evaluate true
         when numfeld < 10     display 'numfeld kleiner als 10'
         when numfeld < 15    display 'numfeld kleiner als 15'
         when other           display 'numfeld >= 15'
        end-evaluate

Wertetabellen lassen sich mit EVALUATE besonders leicht kodieren:

x	y	z	Ergebnis
10	4	8	1
10	5	3	2
20	7	7	3
30	7	9	4
30	8	4	5
beliebig 1	1	beliebig	6
sonst			0


       identification division.
       environment division.
       data division.
       working-storage section.
       01 x            pic 99.
       01 y            pic 99.
       01 z            pic 99.
       01 erg          pic 99.
       procedure division.


        move 10 to x.
        move 0 to y z.
        perform check.


        move 4 to y.
        move 8 to z.
        perform check.


        move 5 to y.
        move 3 to z.
        perform check.


        move 20 to x.
        move 7 to y z.
        perform check.


        move 30 to x.
        move 9 to z.
        perform check.


        move 8 to y.
        move 4 to z.
        perform check.



        move 12 to x
        move 11 to y.
        perform check.


        move 5 to z
        move 12 to y.
        perform check.



        call getchar.


       check section.


        evaluate x    also y       also z
         when 10      also 4       also 8       move 1 to erg
         when 10      also 5       also 3       move 2 to erg
         when 20      also 7       also 7       move 3 to erg
         when 30      also 7       also 9       move 4 to erg
         when 30      also 8       also 4       move 5 to erg
         when any     also 11      also any     move 6 to erg
         when other                             move 0 to erg
        end-evaluate


        display x ' ' y ' ' z  ' --> ' erg.

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