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備考
COBOL SEARCHステートメントには2つの形式があります。線形トップSEARCHボトムSEARCHとバイナリSEARCH ALLアルゴリズム。バイナリSEARCH ALLは、要素の順不同でバイナリ検索に適したソートされたテーブルを想定しています。
SEARCH文
リニアサーチ
バイナリ検索ALL
リニアサーチ
GCobol >>SOURCE FORMAT IS FIXED
*> ***************************************************************
*> Purpose: Demonstration of the SEARCH verb
*> Tectonics: cobc -x searchlinear.cob
*> ***************************************************************
identification division.
program-id. searchlinear.
data division.
working-storage section.
01 taxinfo.
05 tax-table occurs 4 times indexed by tt-index.
10 province pic x(2).
10 taxrate pic 999v9999.
10 federal pic 999v9999.
01 prov pic x(2).
01 percent pic 999v9999.
01 percentage pic zz9.99.
*> ***************************************************************
procedure division.
begin.
*> ***************************************************************
*> Sample for linear SEARCH, requires INDEXED BY table
*> populate the provincial tax table;
*> *** (not really, only a couple of sample provinces) ***
*> populate Ontario and PEI using different field loaders
move 'AB' to province(1)
move 'ON' to province(2)
move 0.08 to taxrate(2)
move 0.05 to federal(2)
move 'PE00014000000000' to tax-table(3)
move 'YT' to province(4)
*> Find Ontario tax rate
move "ON" to prov
perform search-for-taxrate
*> Setup for Prince Edward Island
move 'PE' to prov
perform search-for-taxrate
*> Setup for failure
move 'ZZ' to prov
perform search-for-taxrate
goback.
*> ***************************************************************
search-for-taxrate.
set tt-index to 1
search tax-table
at end display "no province: " prov end-display
when province(tt-index) = prov
perform display-taxrate
end-search
.
display-taxrate.
compute percent = taxrate(tt-index) * 100
move percent to percentage
display
"found: " prov " at " taxrate(tt-index)
"," percentage "%, federal rate of " federal(tt-index)
end-display
.
end program searchlinear.
バイナリ検索ALL
GCobol >>SOURCE FORMAT IS FIXED
*> ***************************************************************
*> Purpose: Demonstration of the SEARCH ALL verb and table SORT
*> Tectonics: cobc -x -fdebugging-line searchbinary.cob
*> ***************************************************************
identification division.
program-id. searchbinary.
environment division.
input-output section.
file-control.
select optional wordfile
assign to infile
organization is line sequential.
data division.
file section.
fd wordfile.
01 wordrec pic x(20).
working-storage section.
01 infile pic x(256) value spaces.
88 defaultfile value '/usr/share/dict/words'.
01 arguments pic x(256).
*> Note the based clause, this memory is initially unallocated
78 maxwords value 500000.
01 wordlist based.
05 word-table occurs maxwords times
depending on wordcount
descending key is wordstr
indexed by wl-index.
10 wordstr pic x(20).
10 wordline usage binary-long.
01 wordcount usage binary-long.
01 file-eof pic 9 value low-value.
88 at-eof value high-values.
01 word pic x(20).
*> ***************************************************************
procedure division.
begin.
*> Get the word file filename
accept arguments from command-line end-accept
if arguments not equal spaces
move arguments to infile
else
set defaultfile to true
end-if
*> ***************************************************************
*> Try playing with the words file and binary SEARCH ALL
*> requires KEY IS and INDEXED BY table description
*> Point wordlist to valid memory
allocate wordlist initialized
open input wordfile
move low-value to file-eof
read wordfile
at end set at-eof to true
end-read
perform
with test before
until at-eof or (wordcount >= maxwords)
add 1 to wordcount
move wordrec to wordstr(wordcount)
move wordcount to wordline(wordcount)
read wordfile
at end set at-eof to true
end-read
end-perform
close wordfile
*> ensure a non-zero length table when allowing optional file
evaluate true also file-eof
when wordcount = 0 also any
move 1 to wordcount
display "No words loaded" end-display
when wordcount >= maxwords also low-value
display "Word list truncated to " maxwords end-display
end-evaluate
>>D display "Count: " wordcount ": " wordstr(wordcount) end-display
*> Sort the words from z to a
sort word-table on descending key wordstr
*> fetch a word to search for
display "word to find: " with no advancing end-display
accept word end-accept
*> binary search the words for word typed in and display
*> the original line number if/when a match is found
set wl-index to 1
search all word-table
at end
display
word " not a word of " function trim(infile)
end-display
when wordstr(wl-index) = word
display
word " sorted to " wl-index ", originally "
wordline(wl-index) " of " function trim(infile)
end-display
end-search
*> Release memory ownership
free address of wordlist
goback.
end program searchbinary.
Modified text is an extract of the original Stack Overflow Documentation
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