China DOS Union

There are a few issues with your code. Here's the corrected version:

```batch
@echo off
if exist z:\ (
echo You have drive Z:
) else (
echo You don't have drive Z:
)
pause
```

The problem with your original code is that simply doing `z:` doesn't properly check if the drive exists in a reliable way. The `if exist` command is a better and more straightforward way to check if a drive or directory exists.

Because CMD executes in top-to-bottom order - if there are no jump statements like goto in the middle, so when it executes the echo You don't have drive Z: sentence, because there are no jump statements, the program will continue to go down and execute the content of :right.

The solution is: add a line of pause && goto :eof above :right.

I want to ask, what is the error code, 0 or 1, when entering a non-existent drive letter in cmd?
I modified it. The cmd is as follows:

@echo off
z:
IF Errorlevel 0 GOTO error
echo You don't have a z drive
goto exit
:error
echo You have a z drive
:exit
pause

Why is this still not working?

Error codes are rather complicated. Nowadays, users might have forgotten about them. Unfortunately, I haven't had much exposure to them and can't be of much help. I suggest you don't judge by the return code.

Then, how to solve it without using error codes?

Can the brother upstairs give a method?

There are not many return codes found through online searches. You can try this yourself. You can use "if exist z:\nul" to make the judgment.

In my XP system, I can use this statement to judge: if exist z: (echo You have drive Z) else (echo You don't have drive Z). There should be no problem in pure DOS. I don't know in what environment you want to use it.

Got it, I didn't expect that "if exist" can be used like this. I always thought it could only be used to judge whether a file exists.

pushd C:>nul 2>nul && echo Yes ||echo No

Hehe, electronixtar's method is also good, but I don't know if the pushd command exists in pure DOS. After using this command, it's best not to forget to use popd in an appropriate place to return to the current directory.