c++ - C++中的设置列表

Question

我在 C++ 中创建了一个集合列表并充满了元素

std::set<Unit*> myUnits; 

for(std::set<Unit*>::iterator i = myUnits.begin(); i != myUnits.end(); i++) {   
    if() {}
}

所以我想在 if 中检查 setlist 的每个元素，如果必须放入什么？

Answer 1

你可能想要这样的东西：

(*i)->stringVal

Answer 2

Unit* pUnit = *i;会给你一个指向Unit对象的指针。顺便说一句，容器的正确术语是“set”，而不是“setlist”。

Answer 3

我不确切地知道你想要什么，但让我们假设，这个Unit类有一个bool Unit::check()方法。然后你必须写：

if (i->check()) {...}

编辑：对不起，我没有意识到你有一组指针......我不确定那是你真正想要的，因为该组将比较指针地址而不是单元的内容，以便定义它们是否相等。这是一个小代码示例，向您展示如何使用带有 Unit-objects 和指向 Unit-objects 的指针的集合：

class Unit
{
public:
    Unit(unsigned int id, bool c)
    {
    this->id = id; // should be unique
    checked = c;
    }

    bool check() const
    {
    return checked;
    }

    unsigned int getId() const
    {
    return id;
    }

    bool operator<(const Unit &u) const // this is needed for the set<Unit>, otherwise two Units can't be compared
    {
    return this->id < u.id;
    }

private:
    bool checked;
    unsigned int id;
};

void setTest()
{
    set<Unit> myUnits;

    Unit u1(1,true);
    Unit u2(2,false);
    Unit u3(2,true);

    myUnits.insert(u1);
    myUnits.insert(u2);
    myUnits.insert(u3);

   cout << "set<Unit>:" << endl;
   for (std::set<Unit>::iterator it = myUnits.begin(); it != myUnits.end(); ++it)
   {
        if (it->check()) // you can access the Unit-object stored in the set like this...
        {
            cout << "Unit " << it->getId() << ": checked" << endl;
        }
        else
        {
                        // ... or like this
            Unit u = *it;
            cout << "Unit " << u.getId() << ": check failed" << endl;
        }
    }

    set<Unit*> myUnitPtrs;

    myUnitPtrs.insert(&u1);
    myUnitPtrs.insert(&u2);
    myUnitPtrs.insert(&u3);

    cout << "set<Unit*>:" << endl;
    for (std::set<Unit*>::iterator it = myUnitPtrs.begin(); it != myUnitPtrs.end(); ++it)
    {
        if ((*it)->check()) // you can access a Unit-Pointer like this ...
        {
            cout << "Unit " << (*it)->getId() << ": checked" << endl;
        }
        else
        {
            Unit *u = *it; // ... or like this
            cout << "Unit " << u->getId() << ": check failed" << endl;
        }
    }
}

输出应该是：

set<Unit>:
Unit 1: checked
Unit 2: check failed // inserting u3 doesn't change the set as a Unit with id 2 is already present in the set
set<Unit*>:
Unit 1: checked
Unit 2: check failed
Unit 2: checked // now there's two Units with id 2, because u2 and u3 have different adresses