Fix C++ Code Error: 'undefined reference to 'GFile::Flush(gfBlockT*)''

The code provided seems to be missing some necessary declarations and definitions. It's difficult to identify the exact errors without the complete code, but based on the provided code, the following issues can be fixed:

1. Make sure the necessary header files are included at the beginning of the code:

#include <iostream> // or any other required header files

2. Check if the class GFile is properly defined with the required member variables and functions.

3. The declaration and definition of the Flush function should match. Make sure the function declaration is present in the class definition.

4. The FlushAll function should be defined within the GFile class.

Here's an example of how the code could be modified:

#include <iostream> // or any other required header files

class GFile {
public:
    errorT Flush(gfBlockT* blk);
    void FlushAll();
    // Other member variables and functions
};

errorT GFile::Flush(gfBlockT* blk) {
    // Implementation of the Flush function
}

void GFile::FlushAll() {
    Flush(CurrentBlock);
}

int main() {
    // Code implementation
    return 0;
}

Note: Replace // Other member variables and functions with the necessary member variables and functions based on your requirements.