This problem represents a major construct in business programming, so the time you devote to this is well spent.
Input data is usually presented to a pgm in some sort sequence, e.g:
So you have a file level, an acct level, a product level and a date level. These levels are important because they are used to process the breaks in the program.
The general form is as follows:
perform level n until level n-1 is finished
For the file described above the perform sequence would be:
Second question: We haven't read any data yet, how can we test if the levels are finished? We do a priming read outside of the loops, usually in the init or mainline section. After this read, if EOF is detected, an error msg is displayed and the pgm is usually exited because no input data has been provided.
How can the loops be executed if the "is-finished" switch has already been set? They can't. So, we reset the switch before executing each lower level:
Note that the form of each level except the detail level is:
Do pre-break stuff (print rpt heads, save data that won't be available after return from perform, etc.)
Reset the level switch.
Perform the next lower level.
Do post-break stuff (strike and/or zero or roll totals, write total recs, etc.)
At the detail level process the previous rec and read the next rec before exiting.
At entry to each level the record has already been read and is ready for processing.
Here's what a break switch would look like:
You have to ask: What do I do before the breaks; what do I do after. The answers to these questions may differ from project to project, but the basic concept: the cascading perform process is constant.
This is one of the two major batch processing constructs in DP. The other is the file match. When I get some time I'll post something on this.
Let me know if this helps or if you have any questions.
Jack
Input data is usually presented to a pgm in some sort sequence, e.g:
Code:
file
acct#1
product1
date1
date2
etc.
product2
date1
date3
date4
etc.
acct#2
product1
date3
etc.So you have a file level, an acct level, a product level and a date level. These levels are important because they are used to process the breaks in the program.
The general form is as follows:
perform level n until level n-1 is finished
For the file described above the perform sequence would be:
Code:
In the mainline you code:
perform acct-lev until file-is-finished
In the acct-lev you code:
perform prod-lev until acct-is-finished
In the prod-lev you code:
perform date-lev until prod-is-finished
In the date-lev you code:
perform detl-lev until date-is-finished
In the detl-lev you code:
Aggregate all detl recs; aggregate all level totals; etc.
Read next I/P detl rec
OK now lets flesh this out. How do we determine when each level is finished? One way is to expand the function of the read routine to do this:
7000-read-rtn.
move ws-ip-rec to ws-ip-prev
read ip-file into ws-ip-rec
at end set ip-eof to true
move high-values to ws-ip-rec
not at end add +1 to ws-ip-cnt
end-read
perform 7010-set-breaks
.
7010-set-breaks.
if curr-acct not = prev-acct
set acct-is-finished to true
set prod-is-finished to true
set date-is-finished to true
end-if
if curr-prod not = prev-prod
set prod-is-finished to true
set date-is-finished to true
end-if
if curr-date not = prev-date
set date-is-finished to true
end-ifSecond question: We haven't read any data yet, how can we test if the levels are finished? We do a priming read outside of the loops, usually in the init or mainline section. After this read, if EOF is detected, an error msg is displayed and the pgm is usually exited because no input data has been provided.
How can the loops be executed if the "is-finished" switch has already been set? They can't. So, we reset the switch before executing each lower level:
Code:
0000-main-line.
perform 7000-read-ip
if ip-eof
display error msg
stop run
end-if
perform acct-lev until file-is-finished
perform 6900-print-rpt-end
perform 9000-end-it
stop run
.
acct-lev.
perform 6000-print-rpt-heads
set reset-acct-sw to true
perform prod-lev until acct-is-finished
perform 6100-print-acct-tots
zero tots, etc.
.
prod-lev.
set reset-prod-sw to true
perform date-lev until prod-is-finished
.
date-lev.
set reset-date-sw to true
perform detl-lev until date-is-finished
.
detl-lev.
move ip data to rpt-line or whatever
perform 7000-read-ip
.Note that the form of each level except the detail level is:
Do pre-break stuff (print rpt heads, save data that won't be available after return from perform, etc.)
Reset the level switch.
Perform the next lower level.
Do post-break stuff (strike and/or zero or roll totals, write total recs, etc.)
At the detail level process the previous rec and read the next rec before exiting.
At entry to each level the record has already been read and is ready for processing.
Here's what a break switch would look like:
Code:
01 ws-break-switches.
05 ws-acct-sw pic x(001).
88 acct-is-finished value 'f'.
88 reset-acct-sw value 'r'.
This example has 2 break levels so your performs would look like:
0000-mainline.
.
.
.
perform 8000-init
perform 7000-read-ip
if ip-eof
display 'no data in i/p file'
stop run
end-if
preform 1000-process-codes until ip-eof
.
.
.
1000-process-codes.
set reset-code-sw to true
perform 1100-process-detl until code-is-finished
.
1100-process-detl.
collect data, etc.
perform 7000-read-ip
.You have to ask: What do I do before the breaks; what do I do after. The answers to these questions may differ from project to project, but the basic concept: the cascading perform process is constant.
This is one of the two major batch processing constructs in DP. The other is the file match. When I get some time I'll post something on this.
Let me know if this helps or if you have any questions.
Jack