在Win32中管理虚拟内存—

在Win32中管理虚拟内存——举例

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发布时间：2019-06-19

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以下两个编程例子： 整块方式使用虚拟内存页 分块方式使用虚拟内存页 （一）整块方式，分以下两步  (1)预留＋提交  (2)释放#include 
    
     #include 
     
      int main(int argc, char*argv[]){ LPVOID lpvBase;      // base address of the test memory int i; for(i=0; ; i++) {  lpvBase = VirtualAlloc(  // (1)   NULL,     // system selects address   102400,     // size of allocation   MEM_RESERVE|MEM_COMMIT, // allocate reserved and committed pages   PAGE_READWRITE);        // both read and write  if (NULL == lpvBase )  {   printf("call VirtualAlloc fail!\n");   exit(1);  }  else  {   printf("call VirtualAlloc LastError=%d\n", GetLastError());   strcpy((char*)lpvBase, "I am a boy!");   VirtualFree(lpvBase, 0, MEM_RELEASE);// (2)   printf("call VirtualFree LastError=%d\n", GetLastError());  }  Sleep(0); }}　其中，VirtualFree(lpvBase, 0, MEM_RELEASE);　等价于　　　　VirtualFree(lpvBase, 0, MEM_DECOMMIT);　　　　VirtualFree(lpvBase, 0, MEM_RELEASE);　但绝不等价于　　　　VirtualFree(lpvBase, 0, MEM_DECOMMIT\|MEM_RELEASE);　也就是说，*MEM_DECOMMIT\|MEM_RELEASE组合方式是不允许的，造成虚拟内存的泄露。（二）分段方式　(1)预留　(2)提交子页　(3)解除提交　(4)释放#include 
      
       #include 
       
        int main(int argc, char*argv[]){ LPVOID lpvBase, lpPage3;      // base address of the test memory int i; for(i=0; ; i++) {  lpvBase = VirtualAlloc(  // (1)   NULL,     // system selects address   4096*8,     // size of allocation   MEM_RESERVE,   // allocate reserved pages   PAGE_READWRITE);        // both read and write  if (NULL == lpvBase )  {   printf("call VirtualAlloc MEM_RESERVE fail!\n");   exit(1);  }  else  {   printf("call VirtualAlloc MEM_RESERVE, LastError=%d\n", GetLastError());   lpPage3 = VirtualAlloc(   //(2)    (char*)lpvBase+(4096*2), // user selects address    4096,      // size of allocation    MEM_COMMIT,     // allocate committed pages    PAGE_READWRITE);   // both read and write   if (NULL == lpPage3 )   {    printf("call VirtualAlloc MEM_COMMIT fail!\n");    exit(1);   }   printf("call VirtualAlloc MEM_COMMIT, LastError=%d\n", GetLastError());   strcpy((char*)lpPage3, "I am a boy!");   VirtualFree((char*)lpvBase+(4096*2), 4096, MEM_DECOMMIT); //(3)   printf("call VirtualFree MEM_DECOMMIT, LastError=%d\n", GetLastError());   VirtualFree(lpvBase, 0, MEM_RELEASE); //(4)   printf("call VirtualFree MEM_RELEASE, LastError=%d\n", GetLastError());  }  Sleep(0); }}