场景:

1.有时候要对磁盘进行扫描操作，比如一些系统软件需要知道磁盘的信息。这时候就需要获取磁盘的盘符，类型和容量。

文件test_usb.cpp

#include <stdio.h>
#include <stdint.h>
#include <windows.h>
#include <iostream>

using namespace std;

void TestDrive()
{
	cout << "TestDrive" << endl;
	char* lpDrives = (char*)malloc(MAX_PATH*sizeof(char));
	memset(lpDrives,0,MAX_PATH*sizeof(char));

    DWORD dwLen = ::GetLogicalDriveStringsA(MAX_PATH, lpDrives);
	cout << "dwLen: " << dwLen << endl;

    DWORD driver_number = dwLen / 4;
	cout << "driver_number: " << driver_number << endl;

    string driver;
	LPTSTR start;
    for(DWORD nIndex = 0; nIndex < driver_number; nIndex++)
    {
		start = lpDrives + nIndex * 4;
		cout << "........................................." << endl;
		driver.append(start);
		cout << "lpDrives + nIndex * 4: " << lpDrives + nIndex * 4 << endl;
		cout << "DRIVE_REMOVABLE: " << DRIVE_REMOVABLE << endl;
		cout << "::GetDriveType(lpDrives + nIndex * 4): " << ::GetDriveType(lpDrives + nIndex * 4) << endl;
		if(::GetDriveType(start) == DRIVE_REMOVABLE)
        {
			driver.append(start);
			if( GetVolumeInformation(start,0,0,0,0,0,0,0) ) //判断驱动是否准备就绪
			{
				cout << "驱动准备就绪 " << endl;
			}
        }
		uint64_t lpFreeBytesAvailable = 0;
		uint64_t lpTotalNumberOfBytes = 0;
		uint64_t lpTotalNumberOfFreeBytes = 0;
		GetDiskFreeSpaceExA(lpDrives + nIndex * 4,(PULARGE_INTEGER)&lpFreeBytesAvailable,
			(PULARGE_INTEGER)&lpTotalNumberOfBytes,(PULARGE_INTEGER)&lpTotalNumberOfFreeBytes);
		cout << "lpFreeBytesAvailable: " << lpFreeBytesAvailable << endl;
		cout << "lpTotalNumberOfBytes: " << lpTotalNumberOfBytes << endl;
		cout << "lpTotalNumberOfFreeBytes: " << lpTotalNumberOfFreeBytes << endl;
    }
	cout << "driver: " << driver << endl;
}

int main(int argc, char *argv[])
{
	//TestWchar();
	TestDrive();
	
	return 0;
}

输出:

---------- CompileLinkRun ----------
TestDrive
dwLen: 24
driver_number: 6
.........................................
lpDrives + nIndex * 4: C:\
DRIVE_REMOVABLE: 2
::GetDriveType(lpDrives + nIndex * 4): 3
lpFreeBytesAvailable: 12637241344
lpTotalNumberOfBytes: 159210532864
lpTotalNumberOfFreeBytes: 12637241344
.........................................
lpDrives + nIndex * 4: D:\
DRIVE_REMOVABLE: 2
::GetDriveType(lpDrives + nIndex * 4): 5
lpFreeBytesAvailable: 0
lpTotalNumberOfBytes: 0
lpTotalNumberOfFreeBytes: 0
.........................................
lpDrives + nIndex * 4: E:\
DRIVE_REMOVABLE: 2
::GetDriveType(lpDrives + nIndex * 4): 4
lpFreeBytesAvailable: 12637241344
lpTotalNumberOfBytes: 159210532864
lpTotalNumberOfFreeBytes: 12637241344
.........................................
lpDrives + nIndex * 4: F:\
DRIVE_REMOVABLE: 2
::GetDriveType(lpDrives + nIndex * 4): 3
lpFreeBytesAvailable: 52076490752
lpTotalNumberOfBytes: 160000000000
lpTotalNumberOfFreeBytes: 52076490752
.........................................
lpDrives + nIndex * 4: G:\
DRIVE_REMOVABLE: 2
::GetDriveType(lpDrives + nIndex * 4): 5
lpFreeBytesAvailable: 0
lpTotalNumberOfBytes: 0
lpTotalNumberOfFreeBytes: 0
.........................................
lpDrives + nIndex * 4: H:\
DRIVE_REMOVABLE: 2
::GetDriveType(lpDrives + nIndex * 4): 2
驱动准备就绪 
lpFreeBytesAvailable: 3812806656
lpTotalNumberOfBytes: 3860234240
lpTotalNumberOfFreeBytes: 3812806656
driver: C:\D:\E:\F:\G:\H:\H:\

Output completed (4 sec consumed) - Normal Termination