问题
I need to write a unit test for some C++ code that checks for the presence of an environmental variable. I'm using MSVS 2008 and gtest as my framework. I add the environmental variable using putenv, I check the environmental variable using getevn, but I can't figure out how to remove it so that no other test will see it. I realize this is probably easy, but I can't find the answer on the internet. Thanks
回答1:
Calling putenv again specifying "SOME_VAR=" as parameter will delete environment variable SOME_VAR. btw, Microsoft recommends using _putenv as putenv is deprecated.
回答2:
You could always fork/exec a subprocess to do just the putenv/getenv testing, and then when it terminates there isn't any stray environment left around.
回答3:
How about setting the env var to an empty string?
From cmd.exe, this works:
set SOMEVAR=something
echo %SOMEVAR%
set SOMEVAR=
echo %SOMEVAR%
Where the last one shows it has been deleted.
回答4:
you can use the unsetenv function.
If vc2008 lacks this function, you can directly access the environment using getenv_s, and remove the entry manually, simulating unsetenv.
来源：https://stackoverflow.com/questions/3205197/remove-environmental-variable-programmatically