C++ 内存泄漏与映射

我无法清除地图内存（我已通过检查）

我打电话的另一个密码

    Singleton::object _test_object(Singleton::Instance()->insert_new("TEST"));

有什么问题吗？我得到了一个Valgrind错误，比如

      ==19584== 17 bytes in 1 blocks are possibly lost in loss record 31,429 of 52,291
      ==19584==    at 0x69A1642: operator new(unsigned int) (vg_replace_malloc.c:255)
      ==19584==    by 0x772CB0A: std::string::_Rep::_S_create(unsigned int, unsigned int, std::allocator<char> const&) (in /usr/lib/libstdc++.so.6.0.8)
      ==19584==    by 0x772D904: ??? (in /usr/lib/libstdc++.so.6.0.8)
       ==19584==    by 0x772DB16: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, std::allocator<char> const&) (in /usr/lib/libstdc++.so.6.0.8)
       ==19584==    by 0xBF1BC17: test::test() (test.C:34)
       ==19584==    by 0xBF1DB66: G__testDict_143_0_1(G__value*, char const*, G__param*, int) (testDict.C:190)
       ==19584==    by 0x70EA4E5: Cint::G__ExceptionWrapper(int (*)(G__value*, char const*, G__param*, int), G__value*, char*, G__param*, int) (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x71EF2E4: G__call_cppfunc (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x71C0095: G__interpret_func (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x71AF883: G__getfunction (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x71D8CC1: G__new_operator (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x718D07F: G__getexpr (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x717724E: G__define_var (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x71FDEC6: G__defined_type (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x7201A6D: G__exec_statement (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x71BF6C8: G__interpret_func (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x71AF62F: G__getfunction (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x718437D: G__getitem (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x7189F12: G__getexpr (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
       ==19584==    by 0x719713F: G__calc_internal (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)

==19584==1个块中的17个字节可能在52291的丢失记录31429中丢失
==19584==at 0x69A1642：运算符新（无符号整数）（vg_替换_malloc.c:255）
==19584==by 0x772CB0A:std:：string:：_Rep:：_S_create（unsigned int，unsigned int，std:：allocator const&）（in/usr/lib/libstdc++.so.6.0.8）
==19584==0x772D904:？？？（in/usr/lib/libstdc++.so.6.0.8）
==19584==by 0x772DB16:std:：basic_string:：basic_string（char const*，std:：allocator const&）（in/usr/lib/libstdc++.so.6.0.8）
==19584==by 0xBF1BC17:test:：test（）（test.C:34）
==19584==0xBF1DB66:G_uutestdict_143_0_1（G_u值*，字符常量*，G_u参数*，int）（testDict.C:190）
==19584==0x70EA4E5:Cint:：G_u异常包装（int（*）（G_u值*，char const*，G_u参数*，int），G_u值*，char*，G_u参数*，int）（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/libCint.so）
==19584==0x71EF2E4:G_ucall_cppfunc（在/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so中）
==19584==0x71C0095:G_u解释函数（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==0x71AF883:G_ugetfunction（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==由0x71D8CC1:G_uunew_u运算符（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==0x718D07F:G_ugetexpr（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==0x717724E:G_udefine_var（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==0x71FDEC6:G_u定义的类型（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==0x7201A6D:G_uexec_语句（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==0x71BF6C8:G_uuexploration_func（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==0x71AF62F:G_ugetfunction（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==0x718437D:G_ugetitem（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==0x7189F12:G_ugetexpr（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）
==19584==0x719713F:G_计算内部（in/afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so）

试试：

{
std:：map空映射；
空的映射交换（\u映射）；
}

---

（至少，这是说服标准库容器实际释放内存的常用方法。）

简短回答：
您明确声明但未定义析构函数（忘记了

{}

）

长答案：

您的代码甚至不编译。类析构函数中缺少

{}

，并且

对前面缺少
std:：

已更正并用

main

完成：

#include <map>

class testMap {
  public:
    testMap() {}
    ~testMap() {};

    void insert_map(int, int);

  private:
    std::map<int,int> _map;
};

void testMap::insert_map(int i, int j) {
    _map.insert(std::pair<int, int>(i,j));
}

int main() {
    testMap t;
    t.insert_map(12, 34);
    return 0;
}

在

valgrind

监督下运行：

valgrind ./leak
==20773== Memcheck, a memory error detector
==20773== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
==20773== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info
==20773== Command: ./leak
==20773== 
==20773== 
==20773== HEAP SUMMARY:
==20773==     in use at exit: 0 bytes in 0 blocks
==20773==   total heap usage: 1 allocs, 1 frees, 24 bytes allocated
==20773== 
==20773== All heap blocks were freed -- no leaks are possible
==20773== 
==20773== For counts of detected and suppressed errors, rerun with: -v
==20773== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 17 from 6)

没有内存泄漏

可能编译器自动定义了一个完全空的类析构函数（因为缺少

{}

），在退出私有成员映射析构函数时不再自动调用

---

希望有帮助：）

您从valgrind获得了什么输出？您是否可以显示您正在进行的创建/销毁testMap对象的调用？以及，在地图名称中使用下划线？糟糕@乔治，我也这么想，直到有人告诉我实际的规则——在课堂上是可以的。我认为这是成员变量的一个非常常见的约定。@Sen：您使用了什么编译器？或者更简洁地说，

std:：map（）.swap（_-map）

@ildjarn:Yours的优点是可以立即释放内存，而不是在

empty\u map

超出范围时释放内存。我的优点是，对于不熟悉这个成语的人来说，更容易阅读。“简洁”并不总是“更好”。我从来没有说过“更好”，这是有原因的。我很想知道长的答案，因为我不知道除了生成链接器错误之外，它还有什么坏处。@Mark：我想这里的重点是在出现语法错误的情况下，编译器的奇怪行为。刚才问OP他用的是什么编译器。@Vanni:如果编译器在用户声明析构函数时自动生成析构函数，我会感到震惊。。。应该是链接器错误。但是，+1说明map的一般用法是合理的，给出了一个合理的编译器。

{
    std::map<int,int> empty_map;
    empty_map.swap(_map);
}

#include <map>

class testMap {
  public:
    testMap() {}
    ~testMap() {};

    void insert_map(int, int);

  private:
    std::map<int,int> _map;
};

void testMap::insert_map(int i, int j) {
    _map.insert(std::pair<int, int>(i,j));
}

int main() {
    testMap t;
    t.insert_map(12, 34);
    return 0;
}

g++ leak.cpp -o leak

valgrind ./leak
==20773== Memcheck, a memory error detector
==20773== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
==20773== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info
==20773== Command: ./leak
==20773== 
==20773== 
==20773== HEAP SUMMARY:
==20773==     in use at exit: 0 bytes in 0 blocks
==20773==   total heap usage: 1 allocs, 1 frees, 24 bytes allocated
==20773== 
==20773== All heap blocks were freed -- no leaks are possible
==20773== 
==20773== For counts of detected and suppressed errors, rerun with: -v
==20773== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 17 from 6)