内存分配：更换策略，不要为难内存

 #include <Windows.h>
#include <string>
#include <iostream>

struct Sheet //我们要读取的数据结构
{
int nSize;
BOOL bVisible;
char big[1024 * 15];
std::string strText;
};

int main()
{
SYSTEM_INFO si;
GetSystemInfo(&si);
DWORD dwPageSize = si.dwPageSize; //获得CPU读取的页大小

//把页的单位转为字节（页的单位本来是KB，而我们的数据结构是按字节算的）
DWORD dwPageAsByte = dwPageSize * 1024;

//以下dwOccupy获得一个数据结构所占的空间，由于是按页分配实际内存，这样所占空间并定是页的整数倍
DWORD dwMod = sizeof(Sheet) % dwPageAsByte;
DWORD dwOccupy = 0;
if (dwMod != 0)
{
dwOccupy = (sizeof(Sheet) / dwPageAsByte) * dwPageAsByte + dwPageAsByte;
}
else
{
dwOccupy = sizeof(Sheet);
}

//申请虚拟内存，MEM_RESERVE表示不会和实际内存建立映射关系
LPVOID lpBaseAddr = VirtualAlloc(NULL, dwOccupy * 50, MEM_RESERVE, PAGE_READWRITE);
if (lpBaseAddr == NULL)
{
return 1;
}

__try
{
DWORD dwIndex = 0;

//以下不断的输入要读取哪个数据，若此数据还有没有建立实际内存映射关系，那么建立
while(true)
{
std::cout << "input the sheet number to write: ";
std::cin >> dwIndex;

//根据输入的索引，计算出所要读取的数据结构所在地址，注意同样是按页分配的
LPVOID lpSheetAddr = (LPVOID)((DWORD)lpBaseAddr + (dwIndex - 1) * dwOccupy);

MEMORY_BASIC_INFORMATION mbi;
memset(&mbi, 0, sizeof(mbi));

//查询内存状态
if (VirtualQuery(lpSheetAddr, &mbi, sizeof(mbi)) == sizeof(mbi))
{
if (mbi.State == MEM_RESERVE)//属于reserve状态
{
//建立与实际内存的映射关系
LPVOID lpAlloc = VirtualAlloc(lpSheetAddr, dwOccupy, MEM_COMMIT, PAGE_READWRITE);
if (lpAlloc == NULL)
{
std::cout << "commit fails in reserve state\n";
}
else
{
std::cout << "commit successes in reserve state\n";
}
}
}

//建立成功，读/写数据
Sheet * pSheet = (Sheet*)lpSheetAddr;
pSheet->nSize = 9;
pSheet->strText = "hello world";
pSheet->bVisible = TRUE;

}
}
__except(EXCEPTION_EXECUTE_HANDLER)
{

}

//释放内存
VirtualFree(lpBaseAddr, 0, MEM_RELEASE);
}