cobol
Instrukcja OPEN
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Uwagi
Instrukcja COBOL OPEN inicjuje przetwarzanie pliku. Zasoby plików w języku COBOL są zdefiniowane w ENVIRONMENT DIVISION , nazwane w akapitach FD (deskryptor pliku). Te nazwy fd służą do uzyskiwania dostępu do fizycznych plików dysków, a różne opcje są określone w klauzulach SELECT w akapicie FILE-CONTROL w sekcji INPUT-OUTPUT SECTION . Oczekuje się, że programista przetestuje identyfikator FILE STATUS kątem kodów statusu i błędów.
Tryby obejmują INPUT , OUTPUT , IO i EXTEND .
Próbka OPEN z mini raportem LINAGE
COBOL *****************************************************************
* Example of LINAGE File Descriptor
* Tectonics: $ cocb -x linage.cob
* $ ./linage <filename ["linage.cob"]>
* $ cat -n mini-report
*****************************************************************
IDENTIFICATION DIVISION.
PROGRAM-ID. linage-demo.
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
select optional data-file assign to file-name
organization is line sequential
file status is data-file-status.
select mini-report assign to "mini-report".
DATA DIVISION.
FILE SECTION.
FD data-file.
01 data-record.
88 endofdata value high-values.
02 data-line pic x(80).
FD mini-report
linage is 16 lines
with footing at 15
lines at top 2
lines at bottom 2.
01 report-line pic x(80).
WORKING-STORAGE SECTION.
01 command-arguments pic x(1024).
01 file-name pic x(160).
01 data-file-status pic 99.
01 lc pic 99.
01 report-line-blank.
02 filler pic x(18) value all "*".
02 filler pic x(05) value spaces.
02 filler pic x(34)
VALUE "THIS PAGE INTENTIONALLY LEFT BLANK".
02 filler pic x(05) value spaces.
02 filler pic x(18) value all "*".
01 report-line-data.
02 body-tag pic 9(6).
02 line-3 pic x(74).
01 report-line-header.
02 filler pic x(6) VALUE "PAGE: ".
02 page-no pic 9999.
02 filler pic x(24).
02 filler pic x(5) VALUE " LC: ".
02 header-tag pic 9(6).
02 filler pic x(23).
02 filler pic x(6) VALUE "DATE: ".
02 page-date pic x(6).
01 page-count pic 9999.
PROCEDURE DIVISION.
accept command-arguments from command-line end-accept.
string
command-arguments delimited by space
into file-name
end-string.
if file-name equal spaces
move "linage.cob" to file-name
end-if.
open input data-file.
read data-file
at end
display "File: " function trim(file-name) " open error"
go to early-exit
end-read.
open output mini-report.
write report-line
from report-line-blank
end-write.
move 1 to page-count.
accept page-date from date end-accept.
move page-count to page-no.
write report-line
from report-line-header
after advancing page
end-write.
perform readwrite-loop until endofdata.
display
"Normal termination, file name: "
function trim(file-name)
" ending status: "
data-file-status
close mini-report.
* Goto considered harmful? Bah! :)
early-exit.
close data-file.
exit program.
stop run.
****************************************************************
readwrite-loop.
move data-record to report-line-data
move linage-counter to body-tag
write report-line from report-line-data
end-of-page
add 1 to page-count end-add
move page-count to page-no
move linage-counter to header-tag
write report-line from report-line-header
after advancing page
end-write
end-write
read data-file
at end set endofdata to true
end-read
.
*****************************************************************
* Commentary
* LINAGE is set at a 20 line logical page
* 16 body lines
* 2 top lines
* A footer line at 15 (inside the body count)
* 2 bottom lines
* Build with:
* $ cobc -x -Wall -Wtruncate linage.cob
* Evaluate with:
* $ ./linage
* This will read in linage.cob and produce a useless mini-report
* $ cat -n mini-report
*****************************************************************
END PROGRAM linage-demo.
Modified text is an extract of the original Stack Overflow Documentation
Licencjonowany na podstawie CC BY-SA 3.0
Nie związany z Stack Overflow