What syntax will check if a variable name containing spaces is defined?

Question

Windows user defined environment variable names can contain any character except =.

Special characters can be included by escaping them. A simpler metho

Answer 1

I do it by defining a flag as TRUE if needed...

rem /* sample code */
set VAR_SET=
if  set VAR_SET=TRUE&set VAR=this data has spaces

rem /* test for VAR_SET using 'if defined' */
if defined VAR_SET (
  rem /* do something with the other data in the variable %VAR% */
)

rem /* clear the flag */
set VAR_SET=