how concatenate two variables in batch script?

Question

I want to do something like this in batch script. Please let me know if this is the proper or possible way to do it or any other way?

set var1=A

set var2=B

set AB=hi

set newvar=%var1%%var2%

echo %newvar%

This should produce the value "hi".

score 27 · Accepted Answer · answered Oct 21 '11 at 08:44

27

Enabling delayed variable expansion solves you problem, the script produces "hi":

setlocal EnableDelayedExpansion

set var1=A
set var2=B

set AB=hi

set newvar=!%var1%%var2%!

echo %newvar%

answered Oct 21 '11 at 08:44

Sergey Podobry

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2

Thank you!!! it worked!! For disabling just to do is "setlocal DisableDelayedExpansion"? – Kantesh Oct 21 '11 at 08:48
1

No, you need to call endlocal. But beware that all variables in setlocal-endlocal block are local and not available from outside. You can save needed variables as described in http://stackoverflow.com/questions/3262287/make-an-environment-variable-survive-endlocal – Sergey Podobry Oct 21 '11 at 10:12
You may review a more detailed description of this matter in [this question](http://stackoverflow.com/questions/7882395/why-is-delayed-expansion-in-a-batch-file-not-working-in-this-case) – Aacini Oct 27 '11 at 01:45

score 11 · Answer 2 · answered Apr 30 '16 at 12:48

11

You can do it without setlocal, because of the setlocal command the variable won't survive an endlocal because it was created in setlocal. In this way the variable will be defined the right way.

To do that use this code:

set var1=A

set var2=B

set AB=hi

call set newvar=%%%var1%%var2%%%

echo %newvar%

Note: You MUST use call before you set the variable or it won't work.

answered Apr 30 '16 at 12:48

1

This is much more interesting than the vanilla `setlocal enabledelayedexpansion`. It also works with global variables. – ender_scythe Nov 03 '16 at 23:04
5

can you explain why we need to call `call` before `set` in the fourth line but not in the first three? – R. Bourgeon Oct 18 '18 at 05:42

jeb · Answer 3 · 2011-10-21T10:38:31.980

5

The way is correct, but can be improved a bit with the extended set-syntax.

set "var=xyz"

Sets the var to the content until the last quotation mark, this ensures that no "hidden" spaces are appended.

Your code would look like

set "var1=A"
set "var2=B"
set "AB=hi"
set "newvar=%var1%%var2%"
echo %newvar% is the concat of var1 and var2
echo !%newvar%! is the indirect content of newvar

edited Oct 21 '11 at 10:38

answered Oct 21 '11 at 08:28

jeb

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It doesn't echo the value "hi" instead it echos AB – Kantesh Oct 21 '11 at 08:41
You are right, I didn't read the last sentence, I only see the question about concatenating – jeb Oct 21 '11 at 10:36

how concatenate two variables in batch script?

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