c++ - 删除传递给构造函数的对象指针导致错误

Question

我是 C++ 的新手，所以我正在尝试借助维基百科的示例来学习它。我玩了一些类(class)，但遇到了段错误。

这是我的代码:

class SomeClass {};

class AnotherClass {
    SomeClass* sc
    public:
        AnotherClass(SomeClass* SC):( sc = SC; ){}

        //***********************************************************************
        ~AnotherClass(){ delete sc; } //here I'm getting rid of internal pointer
        //***********************************************************************
};

int main( int argc, char* argv[] ) {
    SomeClass* SC = new SomeClass();
    AnotherClass* AC = new AnotherClass(SC);

    delete AC;

    // *****************************************************
    delete SC; //i think that this line might cause an error
    //******************************************************

    return 0;
}

我想，我应该删除每个指针来释放堆内存？!能否请您指出我的错误。

编辑:

这是我的真实代码:

#include <iostream>
#include <string>

using namespace std;

class Pizza {
    string dough;
    public:
        Pizza(string d):dough(d) {}
            void setDough( string value ) { dough = value; }
            string getDough() { return dough; }
};

class PizzaBuilder {
    Pizza* pizza;

    public:
        PizzaBuilder( Pizza* p ) { pizza = p; }
        ~PizzaBuilder() { delete pizza; cout << "PizzaBuilder Destructor." << endl;}

        PizzaBuilder* addExtra(string extra) { 
            string special = pizza->getDough() + " and extra " + extra;
            pizza->setDough(special);
            return this;
        }
        Pizza* getPizza() { return pizza; }
    };

int main(int argc, char* argv[]) {

    Pizza* p = new Pizza("My Special DOVE!");
    PizzaBuilder* pb = new PizzaBuilder(p);

    pb->addExtra("Mushrooms")->addExtra("Anchovies")->addExtra("Zefir")->addExtra("Chilli");

    cout << p->getDough() << endl;

    delete pb;
    delete p;

    return 0;
}

Answer 1

delete 并不像您想象的那样删除指针。它删除指针指向的对象。因此，您要删除 SC 指向的对象两次:一次来自 main，另一次来自 AC 指向的对象的析构函数，当删除它。

并且多次删除一个对象是未定义的行为。