TCL : Concatenate a variable and a string

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开发者_Python百科 dont want to specify $u instead i want the direct string to used..

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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).

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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

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Or，you can use format

set b [format %s%s $a $u]

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From Tcl 8.6.2 onwards, there is string cat which can be used to solve this problem.

set b [string cat $a 9876]

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Other option is to use concat command like below.

set b [concat $a\9876]

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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.

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set myString "Hello"

append myString " World!"

puts "$myString"

Hello World!