extra tokens at end of #ifndef directive
时间: 2024-02-01 21:15:38 浏览: 30
In C/C++, the #ifndef directive is used to check if a given macro has already been defined. If it hasn't, the code inside the #ifndef block is executed.
If you're seeing an "extra tokens at end of #ifndef directive" error, it usually means that there are extra characters after the macro name in the #ifndef statement. For example, consider the following code:
```
#ifndef MY_MACRO extra_tokens
// some code here
#endif
```
In this case, the preprocessor will see "MY_MACRO extra_tokens" as a single token, which is not what you intended. To fix this error, make sure that there are no extra characters after the macro name in the #ifndef statement:
```
#ifndef MY_MACRO
// some code here
#endif
```
If you still can't find the issue, try looking for any stray characters or misspelled macro names in your code.