Difference between set and append

[David Teh]

Hi folks,

Is there a difference between the below:

#1

set finalmsgf [concat $mshsr$PIDsegmentallr$PV1segmentallr$restmsgr]

#2

set finalmsg1 [concat $mshsr$PIDsegmentallr$PV1segmentallr$restmsg]

append finalmsgf “$finalmsg1r”

The above is the only difference between 2 tclprocs that I am testing.

Oddly, the output of #1 is missing the x0d at the end of message.

Any ideas?

TIA!

Topic

[James Cobane]

The concat command is used to join “lists” together; the append command is used to join values to a variable.  So, depending on what your desired result is, you need to use the appropriate command.

[David Teh]

Just curious, in this case:

set finalmsgf [concat $mshsr$PIDsegmentallr$PV1segmentallr$restmsgr]

would that last ‘r’ be ‘added’ to finalmsgf, or left out?

TIA!

[David Teh]

Ok, just to answer my last question…

set finalmsgf [concat $mshsr$PIDsegmentallr$PV1segmentallr$restmsgr]

That last statement won’t work.

We would need to do something like this:

set finalmsgf [concat $mshsr$PIDsegmentallr$PV1segmentallr$restmsg]

append finalmsgf “r”

Thanks folks!

[James Cobane]

A solution would be:

set finalmsgf [join “$mshs $PIDsegmentall $PV1segmentall $restmsg” r]

where “$mshs $PIDsegmentall $PV1segmentall $restmsg” is a list and the ‘join’ command creates a single element from the list with a r between each of the original list elements.

[Robert Milfajt]

A couple of things.  The method James suggested,

set finalmsgf [join “$mshs $PIDsegmentall $PV1segmentall $restmsg” r]

leaves off the trailing r and strips out the from the MSH segment, at least in my testing using hcitcl.  I’m guessing the latter is a result of the fact that is an escape character.

For Dave’s dillemma, I’m not sure why the r is not being included with the concat command, but if you use the cconcat command, which I tried, you do get the r at the end of the result.

Both

set finalmsgf [cconcat $mshsr$PIDsegmentallr$PV1segmentallr$restmsgr]

and

set finalmsgf [cconcat $mshs “r” $PIDsegmentall  “r” $PV1segmentall “r” $restmsg”r”]

Gave the final message with trailing x0d character.

The only difference I could see regarding concat and cconcat in the help was that concat will eliminate any leading or trailing spaces.  Perhaps its treating the final “r” as white space and eliminating it.

Hope this helps.

Bob

Robert Milfajt
Northwestern Medicine
Chicago, IL

[Nathan Martin]

I noticed a few examples in this thread that appear to be mixing lists and strings.

[David Teh]

Hi folks,

BIG THANKS!

[Author]

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