>>>>SNIP
>>>>>
>>>>>I think George Tasker hit the nail on the head in an earlier message: that he considers them the equivalent of GOTO in Basic - with all the problems that causes.
>>>>>
>>>>C'mon Al, it's nothing of the sort.
>>>>
>>>>Goto can end up anywhere while LOOP goes to only one place and EXIT goes *only* to the place that you are going to go to anyways. There's a HUGE difference.
>>>>I'm not arguing against your personal standard, just the justification you (and George) use for this particular one.
>>>
>>>Whoa there, bucko. First, you do know where a GOTO will end up: either at the line number or line label. Second, the objection to it and EXIT and LOOP is exactly the same. It leads to un-structured code that's more difficult to both read and maintain.
>>
>>George,
>>
>>How would you program the following piece of code? Requirements:
>>
>>1) If user hits ESC, question is asked (this is procedure of oValid object) and if he/she answers "Yes", code should stop.
>>
>>2) It table could not be opened exclusively, it should be written in the log and proceed with the next.
>>
>>

>>* support user Escapes for interrupting the main loop
>>lcOldOnEsc = on('escape')                    && save previous Escape handler
>>lcOldSetEscape = set('escape')               && previous Escape enablement state
>>set escape on                                   && enable escape handling
>>on escape oValid.StopProcess("Are you sure you want to stop Modify Process?")     && Allows for stopping of the process.
>>do while oValid.lContinue && Till termination
>>     for lnI=1 to m.tnCount     && loop for all selected databases
>>          if not oValid.lContinue
>>               exit
>>          endif
>>          if not file(forceext(taDBC[m.lnI],'DBC'))
>>               =messagebox("Database "+taDBC[m.lnI]+" is not found!",48,"File does not exist")
>>               loop
>>          endif
>>          llDBCExist=.t.
>>          if GetDBC(alltrim(taDBC[m.lnI])) && Opens the database for possible changes && should be in the path
>>               lcDBCPath=addbs(justpath(fullpath(alltrim(taDBC[m.lnI]))))
>>               if !empty(m.lcWholeLogStr) && Separate Databases
>>                    lcWholeLogStr=m.lcWholeLogStr+CR+replicate("*",65)+CR
>>               else
>>                    lcWholeLogStr=upper("Starting checking "+ m.tcAction+" at ")+ttoc(m.lnStartTime)+CR
>>               endif
>>               lcWholeLogStr= m.lcWholeLogStr+ttoc(datetime())+" Database: "+alltrim(taDBC[m.lnI])
>>               release laTables
>>               lnTables=adbobjects(laTables, "TABLE")  && Create list of all tables in Database
>>               =asort(laTables)
>>               for lnK=1 to m.lnTables
>>                    if not oValid.lContinue
>>                         exit
>>                    endif
>>                    lcTableName=upper(alltrim(laTables[m.lnK]))
>>                    lnMinSize=3*(GetFileSize(m.lcDBCPath+m.lcTableName+".DBF")+ ;
>>                         GetFileSize(m.lcDBCPath+m.lcTableName+".FPT") + ;
>>                         GetFileSize(m.lcDBCPath+m.lcTableName+".CDX"))
>>                    if vartype(m.pcTempDrive)"C"
>>                         pcTempDrive=justdrive(sys(2023))
>>                    endif
>>                    if GetFreeSpace(m.pcTempDrive, m.llFirstTime)>                         =messagebox("Could not check and possibly alter "+m.lcTableName+" because it's not enough free space!"+CR + ;
>>                              "Free space, then repeat the process!",48,"Not enough space")
>>                         llStop=.t.
>>                         exit
>>                    else
>>                         llTableOpened=.f.
>>                         if m.lcTableName"NEXTID"
>>                              if OpenTble(m.lcTableName,'WorkFile','exclusive') && Open Table excl with alias WorkFile
>>                                   lcWholeLogStr= m.lcWholeLogStr+CR+"Table: "+ m.lcTableName+ ;
>>                                        " starting checking "+m.tcAction+" at "+ttoc(datetime())+CR
>>                                   llTableOpened=.t.
>>                                   if m.tcAction='Structure'
>>                                        =Modify_Structure(m.lcTableName, alltrim(taDBC[m.lnI]), @lcWholeLogStr)
>>                                   endif   && Structure changes only
>>                                   lcWholeLogStr= m.lcWholeLogStr+CR+"Table: "+m.lcTableName+ ;
>>                                        " starting checking indexes at "+ttoc(datetime())+CR
>>                                   =Modify_Indexes(m.lcTableName, alltrim(taDBC[m.lnI]), @lcWholeLogStr)
>>                                   use     in select('WorkFile')
>>                                   flush
>>                              else && Table was not opened
>>                                   lcWholeLogStr= m.lcWholeLogStr+  ;
>>                                        ttoc(datetime())+" Table "+ m.lcTableName+ ;
>>                                        " was opened by another user and therefore was not checked..."+ ;
>>                                        +CR+replicate("_",65)+CR
>>
>>                              endif
>>                         endif
>>                         llFirstTime=.f.
>>                    endif
>>               endfor      && End loop for all tables within Database
>>               if oValid.lContinue
>>                    lcWholeLogStr= m.lcWholeLogStr+  ;
>>                         ttoc(datetime())+" Finished checking all tables in "+alltrim(taDBC[m.lni])+CR
>>               endif
>>               close database
>>               lcDBCPath=addbs(justpath(fullpath(forceext(taDBC[lni],'DBC'))))
>>               erase (m.lcDBCPath+'*.bak')
>>               erase (m.lcDBCPath+'*.tbk')
>>          endif
>>     endfor     &&   End loop for all selected databases
>>     exit
>>enddo

>>
>>Thanks in advance.
>
>Nadya,
>
>If you really want my advice, I'll be happy to give it to you. It, however, may not be possible to accurately evaluate this without my asking for additional information. What I'll do is base it entirely on what's shown, if you have any questions then, I'll probably need more information.


George,

The question here is simple: how can you terminate the inner loop, if user pressed ESC? I believe these two constructs are equal, so both are not permitted in your code:

for i=1 to m.lnCount
   if somecondition
        exit
   endif
   .......
next

or

for i=1 to m.lnCount
   if somecondition
        i=m.lnCount+1 && automatically closed the loop ?
   endif
   .......
next

or

i=0
do while not somecondition or i<=lnCount
   i=i+1
   .....
enddo

Or can you suggest something more clever? Which kind of solution would you choose? Remember, you're doing loop inside of loop inside of loop...

Thanks a lot in advance.