How to set a global variable from inside a loop

So here is the batch code I am using.

set fullstring=
set string=testago
echo %string%>x&FOR %%? IN (x) DO SET /A strlength=%%~z? - 2&del x

for /L %%a in (1,1,%strlength%) do (
set b=%%a - 1
set c=%%a
set this=%string:~%%b,%%c%
set fullstring=!fullstring!%this%
)

echo %fullstring%
pause


What this does is read back a string (string) character-by-character to another one (fullstring). I need to know how to overwrite the fullstring from the for loop.

for

set

for /L

for /?

set /?

SETLOCAL

1 Answer
1

@echo off
setlocal enabledelayedexpansion

set "fullstring="
set "string=testago"

> x echo %string%

for %%? in (x) do set /a "strlength=%%~z? - 2"

del x

for /l %%a in (1,1,%strlength%) do (
set /a "b=%%a - 1"
call set "this=%%string:~!b!,1%%"
set "fullstring=!fullstring!!this!"
)

echo "%fullstring%"
pause


In the for /l loop, no need for c variable so removed.

for /l

c

Use of call set to do a 2nd parse of the line to set this variable.
b requires delayed expansion then string variable needs expanding so
use of call set on string using doubled percentages achieves this.

call set

this

b

string

call set

string

The 2nd argument of the variable substitution is the length.
Character by character will be a constant 1 for length.

Concatenating the full string will require delayed expansion
or use of call set as an alternative.

call set

Thanks for contributing an answer to Stack Overflow!

But avoid …

To learn more, see our tips on writing great answers.

Some of your past answers have not been well-received, and you're in danger of being blocked from answering.

Please pay close attention to the following guidance:

But avoid …

To learn more, see our tips on writing great answers.

Required, but never shown

Required, but never shown

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.