类静态指针的申请和释放

     如果类有一个静态成员指针变量，在进程中执行new或malloc操作分配了内存，进程退出前并不需要调用new或malloc，因为系统会自动进行释放。但这个静态成员指针变量需要多少分配，又应该如果处理呢，最近在项目代码中看到这样的例子，和大家分享一下。

 

    #include #include class CPointer { public: CPointer(){}; ~CPointer(){}; public: static char * m_p; }; char * CPointer::m_p = NULL; void proc() { for(int i = 0; i < 10; i++) { CPointer::m_p = new char[1024*1024]; sleep(1); } } int main(int argc, char ** argv) { proc(); return 0; }

 

    用valgrind执行，会发现内存泄漏，如下所示，当然，这是很显然的，多次new但没有delete。

 

valgrind --tool=memcheck --leak-check=full  ./a.out

 

==3893== LEAK SUMMARY:
==3893==    definitely lost: 5,242,880 bytes in 5 blocks.
==3893==      possibly lost: 4,194,304 bytes in 4 blocks.
==3893==    still reachable: 1,048,576 bytes in 1 blocks.
==3893==         suppressed: 0 bytes in 0 blocks.
==3893== Reachable blocks (those to which a pointer was found) are not shown.
==3893== To see them, rerun with: --show-reachable=yes

 

    那应该如何解决呢，当然是应该delete，但是类的静态成员在类的生命周期中是不能delete的，感兴趣的朋友可以试下，进程会core。

    但是可以把静态指针赋给另一个局部指针，把局部指针释放掉，这样，即保存了静态指针，同时，资源也得释放。修改代码如下：

 

    #include #include class CPointer { public: CPointer(){}; ~CPointer(){}; public: static char * m_p; }; char * CPointer::m_p = NULL; void proc() { for(int i = 0; i < 10; i++) { if (NULL != CPointer::m_p) { char * p = CPointer::m_p; delete []p; p = NULL; CPointer::m_p = NULL; } CPointer::m_p = new char[1024*1024]; sleep(1); } } int main(int argc, char ** argv) { proc(); return 0; }

 

   再用valgrind执行，问题解决。

 

==3912== LEAK SUMMARY:
==3912==    definitely lost: 0 bytes in 0 blocks.
==3912==      possibly lost: 0 bytes in 0 blocks.
==3912==    still reachable: 1,048,576 bytes in 1 blocks.
==3912==         suppressed: 0 bytes in 0 blocks.
==3912== Reachable blocks (those to which a pointer was found) are not shown.
==3912== To see them, rerun with: --show-reachable=yes