错误C4430：缺少类型说明符

Question

When trying to compile this project, I get 2 errors that I can't figure how to solve.

1>initialization.h(6): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 
1>initialization.h(6): error C2146: syntax error : missing ',' before identifier 'diskSpaceNeeded'

Here is the file where the error happens:

Initialization.h

#pragma once
extern bool CheckStorage(const DWORDLONG diskSpaceNeeded);

Initialization.cpp

#include "Initialization.h"
#include "../Main/EngineStd.h"
#include <shlobj.h>
#include <direct.h>

//
// CheckStorage
//
bool CheckStorage(const DWORDLONG diskSpaceNeeded)
{
    // Check for enough free disk space on the current disk.
    int const drive = _getdrive();
    struct _diskfree_t diskfree;

    _getdiskfree(drive, &diskfree);

    unsigned __int64 const neededClusters = 
        diskSpaceNeeded /(diskfree.sectors_per_cluster*diskfree.bytes_per_sector);

    if (diskfree.avail_clusters < neededClusters)
    {
        // if you get here you don’t have enough disk space!
        ENG_ERROR("CheckStorage Failure: Not enough physical storage.");
        return false;
    }
    return true;
}

I think it's something wrong with the includes, but I can't find where the error is occurring.

Answer 1

Your Initialization.h uses DWORDLONG which is not part of the C++ standard. This means you need to define it before you can use it.

However, your Initialization.cpp includes Initialization.h first and then includes ../Main/EngineStd.h which defines the Windows specific stuff. Therefore the compiler complains when trying to parse the includes in the order you gave them.

This is also the reason why it works when you switch the order to include ../Main/EngineStd.h before Initialization.h.

It is usually considered good practice that include files include the things that they are using by themselves. So your Initialization.h should contain an include directive for the file that is defining DWORDLONG . Your current solution might work but it will give you a headache when you try to include Initialization.h somewhere else and don't remember which other includes it requires.