试图理解为什么多重映射会像它那样构造/解构
我先给你打印了所有“地址”。我想理解的是为什么它当时要分配。我在构造函数中使用字符串和对象构造了一个多重映射；这个对象的析构函数在被调用时我有一个打印输出。
第一个问题：它是复制对象吗？ 第二个问题：为什么我看到的析构函数多于构造函数？ 第三个问题：我从来没有得到我们在下面看到的任何构造函数中列出的地址（最后 5 个）
感谢您帮助我理解这个 multimap 中的构造/销毁。
奥利弗帕
std::multimap <string, TestObject> m;
for(int i = 0; i < 5 ;i++){
TestObjectone("test", i);
m.insert(pair<string, TestObject>(("a" + i), one));
cout << "Single Iteration" << i << endl;
}
拉姆构造函数 test0 0x22ff24 析构函数称为 TestObject：test0 0x22ff08
析构函数称为 TestObject：test0 0x22ff18
单次迭代0
析构函数称为 TestObject：test0 0x22ff24
参数构造函数 test1 0x22ff24
析构函数称为 TestObject：test1 0x22ff08
析构函数称为 TestObject：test1 0x22ff18
单次迭代1
析构函数称为 TestObject：test1 0x22ff24
参数构造函数 test2 0x22ff24
析构函数称为 TestObject：test2 0x22ff08
析构函数称为 TestObject：test2 0x22ff18
单次迭代2
析构函数称为 TestObject：test2 0x22ff24
参数构造函数 test3 0x22ff24
析构函数称为 TestObject：test3 0x22ff08
析构函数称为 TestObject：test3 0x22ff18
单次迭代3
析构函数称为 TestObject：test3 0x22ff24
参数构造函数 test4 0x22ff24
析构函数称为 TestObject：test4 0x22ff08
析构函数称为 TestObject：test4 0x22ff18
单次迭代4
析构函数称为 TestObject：test4 0x22ff24
析构函数称为 TestObject：test4 0x482f6c
析构函数称为 TestObject：test3 0x482efc
析构函数称为 TestObject：test0 0x482dd4
析构函数称为 TestObject：test2 0x482e8c
析构函数称为 TestObject：test1 0x482e1c
I have a printout of all the "addresses" for you first. The thing im trying to understand is why is it allocating at the time. I have constructed a multimap with a String and an Object, in the constructor & destructor of this object I have a printout when they are called.
First Question: Is it copying the Object?
Second Question: Why do i see more destructors than constructors?
Third Question: I never get the address listed in any constructor which we see below (last 5)
Thanks for helping me to understand this construction/destruction in multimap .
Oliver
std::multimap <string, TestObject> m;
for(int i = 0; i < 5 ;i++){
TestObjectone("test", i);
m.insert(pair<string, TestObject>(("a" + i), one));
cout << "Single Iteration" << i << endl;
}
Param constructor test0 0x22ff24
Destructor is called TestObject: test0 0x22ff08
Destructor is called TestObject: test0 0x22ff18
Single Iteration0
Destructor is called TestObject: test0 0x22ff24
Param constructor test1 0x22ff24
Destructor is called TestObject: test1 0x22ff08
Destructor is called TestObject: test1 0x22ff18
Single Iteration1
Destructor is called TestObject: test1 0x22ff24
Param constructor test2 0x22ff24
Destructor is called TestObject: test2 0x22ff08
Destructor is called TestObject: test2 0x22ff18
Single Iteration2
Destructor is called TestObject: test2 0x22ff24
Param constructor test3 0x22ff24
Destructor is called TestObject: test3 0x22ff08
Destructor is called TestObject: test3 0x22ff18
Single Iteration3
Destructor is called TestObject: test3 0x22ff24
Param constructor test4 0x22ff24
Destructor is called TestObject: test4 0x22ff08
Destructor is called TestObject: test4 0x22ff18
Single Iteration4
Destructor is called TestObject: test4 0x22ff24
Destructor is called TestObject: test4 0x482f6c
Destructor is called TestObject: test3 0x482efc
Destructor is called TestObject: test0 0x482dd4
Destructor is called TestObject: test2 0x482e8c
Destructor is called TestObject: test1 0x482e1c
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评论（1）
第一个问题：
是的，STL 容器具有值语义，并且您的对象会被复制。
第二个问题：
可能是因为您的复制构造函数没有调试打印。如果您尚未实现自己的自定义 copy-ctor，则将使用默认的 copy-ctr。
第三个问题：
您会看到复制构造对象的析构函数调用（正如 jkrok 在评论中提到的那样）
First question:
yes, STL-container have a value semantic and your objects are copied.
Second Question:
probably because your Copy Constructor has no debug prints. If you have not implemented your own, custom made copy-ctor, then the defaults copy-ctr will be used.
Third Question:
You see the destructor calls of the copy constructed objects (as also jkrok mentions in the comments)