iskm/learnxinyminutes-docs
1
0
Fork 0
mirror of https://github.com/adambard/learnxinyminutes-docs.git synced 2024-12-23 09:41:36 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Corrections and some added explanation.

Browse Source
This commit is contained in:
Mark Green 2020-04-09 15:20:49 +01:00
parent 5f49e0ade0
commit 912eca480e
1 changed files with 63 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
cobol.html.markdown
View File

@ -7,8 +7,9 @@ filename: learn.COB
COBOL is a business-oriented language revised multiple times since its original design in 1960. It is claimed to still be used in over 80% of
organizations.
```
```cobol
*COBOL. Coding like it's 1985.
*Compiles with GnuCOBOL in OpenCobolIDE 4.7.6.
*COBOL has significant differences between legacy (COBOL-85)
*and modern (COBOL-2002 and COBOL-2014) versions.
@ -40,7 +41,7 @@ organizations.
01 age picture 999. *> A number up to 3 digits.
01 valx picture 999. *> Another number up to 3 digits.
01 inyear picture s9(7). *> S makes number signed.
*> Brackets indicate 6 repeats of 9,
*> Brackets indicate 7 repeats of 9,
*> ie a 6 digit number (not an array).
*Now let's write some code.
@ -69,13 +70,13 @@ organizations.
*> Old style way: doesn't give an index.
perform age times
display "*" with no advancing *> Ie, no newline at end
end-perform.
end-perform
display "." *> Output buffer isn't flushed until newline.
*> New style way: with an index.
perform varying valx from 1 by 1 until valx > age
display valx "-" with no advancing
end-perform.
end-perform
display "."
*> If tests are still good old if tests.
@ -99,6 +100,10 @@ organizations.
subparagraph. *> Marks the top of an internal subprogram.
*> Shares variable score with its caller.
*> Read year from system timer.
*> Remember the whole "year 2000 crisis"? The yyyyddd
*> option was added in response to that.
accept inyear from day yyyyddd.
*> We can do math step-by-step like this...
@ -110,9 +115,6 @@ organizations.
*> Or we can just use expressions.
compute inyear = 1970 - inyear.
*> Note: if inyear has gone negative, its negativity will
*> not appear when printed, because we didn't include an
*> S (sign character) in the PICTURE.
if inyear >= 0 then
display "When you were " inyear ", " with no advancing
else
@ -121,9 +123,12 @@ organizations.
end-if
display "COBOL was the most popular language in the world."
.
. *> You can put the final . on a new line if it's clearer.
*If we want to use a subprogram, we use literally a subprogram.
*This is the entire program layout, repeated for the
*eratosthenes subroutine.
identification division.
program-id. eratosthenes.
@ -133,10 +138,12 @@ organizations.
*We can declare a variable to use as an index for it at the
*same time.
01 sieve pic 9 occurs 999 times indexed by sa, sb.
*> Standard cobol doesn't have a boolean type.
01 pstart pic 999.
01 counter pic 999.
*Our parameters have to be declared in the linkage section.
*Their pictures must match the values they're called with.
linkage section.
01 maxvalue picture 999.