lreplace performs linsert

[Todd Lundstedt]

Cloverleaf 5.5Rev1 on AIX 5.3

What am I missing here…

Code:

tcl>lreplace {a b c d e} 1 1 foo
a foo c d e

All works just as described in the online tclhelp.

However…

Code:

tcl>lreplace {pv1 {} 0 {} x {} {} {000000^xxxxx doctor} {} {} emm} 7 1 {000000^other doctor}
pv1 {} 0 {} x {} {} {000000^other doctor} {000000^xxxxx doctor} {} {} emm

That inserts at index 7 rather than replacing index 7, taking an 11 element list and turning it into a 12 element list.  What tidbit am I missing?

Topic

[Charlie Bursell]

You are mis-reading how to use lreplace.

lreplace   …

If I had a list and wanted to just replace index 7 (0-based) I would:

set newList [lreplace $oldList 7 7 $newValue]

lreplace and linsert both have gotcha’s associated.  If there are not enough items in the list you will get a Tcl error.  For example, in the above if the list had less than 8 items (7, 0-based) you would get a Tcl error.

If there is any doubt here is what I do.  Assume I am going to lreplace index 7 and I am not sure my list will always have that many

while {[llength $oldList] <= 8} {lappend oldList {}} This will save you *MANY* headaches  🙂

[Todd Lundstedt]

Gotcha… I was reading

lreplace string first last

as

lreplace string first length

Thanks, Charlie!

[Author]

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