C++ 遍历指针向量
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原文地址: http://stackoverflow.com/questions/23318875/
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Iterating through a vector of pointers
提问by Red Shift
I'm trying to iterate through a Players hand of cards.
我正在尝试遍历玩家手中的牌。
Player.cpp
播放器.cpp
vector<Card*>::iterator iter;
for(iter = current_cards.begin(); iter != current_cards.end(); iter++) {
cout << iter->display_card() << endl;
}
The iter in
迭代器
cout << iter->display_card() << endl;
currently comes up with the "error: Expression must have pointer-to-class type".
当前出现“错误：表达式必须具有指向类的类型”。
Likewise, current_cards is declared with:
同样， current_cards 声明为：
vector<Card*>current_cards;
Furthermore, the display_card() method is simply:
此外， display_card() 方法很简单：
Card.cpp
卡.cpp
string Card::display_card(){
stringstream s_card_details;
s_card_details << "Colour: " << card_colour << "\n";
s_card_details << "Type: " << card_type << "\n";
return s_card_details.str();
}
I have looked over various resources and everything that has been suggested for similar types of issues hasn't worked for me. Thanks for any help!
我查看了各种资源，针对类似问题提出的所有建议都对我不起作用。谢谢你的帮助！
回答by Reto Koradi
Try this:
尝试这个：
cout << (*iter)->display_card() << endl;
The *operator gives you the item referenced by the iterator, which in your case is a pointer. Then you use the ->to dereference that pointer.
该*运营商给你的迭代器，而你的情况是一个指针引用的项目。然后您使用->来取消引用该指针。
回答by Joky
You have to dereference the iterator to access the pointer:
您必须取消引用迭代器才能访问指针：
#include <vector>
#include <iostream>
class Card {
public:
std::string display_card();
};
int main() {
std::vector<Card*>current_cards;
std::vector<Card*>::iterator iter, end;
for(iter = current_cards.begin(), end = current_cards.end() ; iter != end; ++iter) {
std::cout << (*iter)->display_card() << std::endl;
}
}
Another observation is the iter++which you should avoid in profit of ++iter(see https://stackoverflow.com/a/24904/2077394).
Depending on the container, you may also want to avoid calling end() each iteration.
另一个观察结果是iter++您应该避免的利润++iter（参见https://stackoverflow.com/a/24904/2077394）。根据容器的不同，您可能还希望避免每次迭代都调用 end()。
(By the way it always help to provide a minimal reproducible example like I just wrote when you ask question.)
（顺便说一句，提供一个最小的可重复示例总是有帮助的，就像我刚才在你提问时写的那样。）
回答by Rakib
De-referencing the iterator by iter-> gives a pointer to an object of type Card, you have to write (*iter)->display_card();
通过 iter-> 取消引用迭代器给出一个指向 Card 类型对象的指针，您必须编写 (*iter)->display_card();
