Section: Tcl Built-In Commands (n)
Updated: 8.3
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concat - Join lists together  


concat ?arg arg ...?



This command joins each of its arguments together with spaces after trimming leading and trailing white-space from each of them. If all the arguments are lists, this has the same effect as concatenating them into a single list. It permits any number of arguments; if no args are supplied, the result is an empty string.  


Although concat will concatenate lists (so the command:

concat a b {c d e} {f {g h}}

will return ``a b c d e f {g h}'' as its result), it will also concatenate things that are not lists, and hence the command:

concat " a b {c   " d "  e} f"

will return ``a b {c d e} f'' as its result.

Note that the concatenation does not remove spaces from the middle of its arguments, so the command:

concat "a   b   c" { d e f }

will return ``a b c d e f'' (i.e. with three spaces between the a, the b and the c).



append(n), eval(n)



concatenate, join, lists