Batch file 如何批量测试变量的长度？

我基本上需要测试变量在批处理文件中的时间长度。例如：

@echo off
set /p someVar=""
//some code to figure out how long it is
cls
echo someVar is %length% characters long.
pause
exit

所以如果我打字

Batch files

它会说

someVar is 10 characters long.

---

根据@minitech提供的链接，这里有一个脚本应该可以工作：

@echo off
set /p someVar=""

::some code to figure out how long it is

::Start by writing the file to a temp file
echo %someVar%>"%temp%\tmp.txt" 

:: get the files size in bytes and subtract 3 for the trailing space and newline and delete the temp file
for %%a in (%temp%\tmp.txt) do set /a length=%%~za & set /a length -=3 & del "%temp%\tmp.txt"

cls

echo someVar is %length% characters long.

pause

exit

---

我不是一个批处理脚本编写者，但谷歌给出了这样一个结论：字符串“batchfiles”不是11个字符长吗？