Storage size of ' xxx ' isn ' t known one of the possible causes of problems

Storage size of ' value ' isn ' t known one of the possible causes of problems

It is possible that the header file is not included, so this problem occurs
There are several ways to find out why:
1, if the structure type, type whether or not write wrong;
2, the variable name is not written wrong;
2. Whether the header file is included in the document;
3. Is there a problem with the precompiled declaration of the header file?

Here's a very strange phenomenon, compiled with Eclipse MinGW GCC,

There are #ifdef Win32 #endif in the header file, which defines some structure,

However, if there is no #ifdef Win32 in the. c file, the definition of the struct cannot be found, and the above inexplicable error occurs.

And if you add #ifdef, you'll be fine, don't understand, what do you mean?

Storage size of ' xxx ' isn ' t known one of the possible causes of problems