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Tcl string concatenation
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—
- Two string variables can easily be concatenated as follows:
set alpha "Hel" set beta "lo" puts stdout $alpha$beta
This gives:
Hello
- Another way is to use
append:set alphabeta "Hel" append alphabeta "lo" puts stdout $alpha$beta
This gives:
Hello
- However, when mixing a string variable and a literal string, the result is not what would be expected:
set alpha "Hel" puts stdout $alpha"Hel"
This gives:
Hel"lo"
- It is important to note that the
concattcl function applies on lists. It is possible to concat some strings by using a list but this is not the good way:set alphabeta [concat "Hel" "lo"] puts stdout $alphabeta
This gives a list of two members, displayed with a space between them:
Hel lo
A list can be merged to give a string (here without spaces between members) as follows:
set alphabeta [join [concat "Hel" "lo"] "" puts stdout $alphabeta
This gives:
Hello
However this is not efficient.
- Finally, the simplest way is by using curly braces to separate the variable name:
set alpha "Hel" set alphabeta ${alpha}lo puts stdout $alphabeta
This gives:
Hello
- Conclusion:
- With
append:set alphabeta "Hel" append alphabeta "lo"
- With curly braces:
set alpha "Hel" set alphabeta ${alpha}lo
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This page is part of the Tcl/Tk page of the Airplug documentation.
Back to the Tcl/Tk page /
Back to Airplug documentation page.
