问题
Assume we have a variable 'a' set to 12345 :
set a 12345
Now how do i set a new variable 'b' which contains the value of 'a' and another string say 9876
workaround is something like
set a "12345"
set u "9876"
set b $a$u
but i dont want to specify $u instead i want the direct string to used..
回答1:
You can do:
set b ${a}9876
or, assuming b is either set to the empty string or not defined:
append b $a 9876
The call to append is more efficient when $a is long (see append doc).
回答2:
other option is to use set command. since set a gives value of a we can use it to set value of b like below
set b [set a]9876
回答3:
Or，you can use format
set b [format %s%s $a $u]
回答4:
From Tcl 8.6.2 onwards, there is string cat which can be used to solve this problem.
set b [string cat $a 9876]
回答5:
Other option is to use concat command like below.
set b [concat $a\9876]
回答6:
I don't get what you mean the direct string... I'm not sure if you want... However, if you want the value of 12349876 you can do:
% set b [concat $a$u]
12349876
If you want $a or $u to be part of the string, just add a backslash '\' before the desired variable.
回答7:
set myString "Hello"
append myString " World!"
puts "$myString"
Hello World!
来源：https://stackoverflow.com/questions/5241954/tcl-concatenate-a-variable-and-a-string