如何通过向量调用方法？ [英] How to call a method via a vector?

问题描述

如何调用存储在向量中的对象的方法？以下代码失败...

  ClassA * class_derived_a = new ClassDerivedA; 
 ClassA * class_another_a = new ClassAnotherDerivedA; 
 
 
 
 vector< ClassA *> test_vector; 
 
 test_vector.push_back（class_derived_a）; 
 test_vector.push_back（class_another_a）; 
 
 for（vector< ClassA *> :: iterator it = test_vector.begin（）; it！= test_vector.end（）; it ++）
 it-> printOutput（）; 
  

代码检索到以下错误：

< >

test3.cpp：47：error：请求
成员'printOutput'在'*
it .__ gnu_cxx :: __ normal_iterator< _Iterator，_Container> :: operator-> _Iterator = ClassA **，_Container = std :: vector>'，其中
是非类类型'ClassA *'

问题似乎是 it-> printOutput（）; 但是目前我不知道如何正确调用该方法，有谁知道？ / p>

关于mikey

解决方案

向量中的东西是指针。您需要：

 （* it） - > printOutput 
  

它引用迭代器从向量中获取指针，然后使用 - >功能。如果向量包含对象而不是指针，那么您在问题中显示的语法将有效。在这种情况下，迭代器就像指向这些对象之一的指针。

How do I call a method of an object which is stored within a vector? The following code fails...

    ClassA* class_derived_a = new ClassDerivedA;
    ClassA* class_another_a = new ClassAnotherDerivedA;



  vector<ClassA*> test_vector;

  test_vector.push_back(class_derived_a);
  test_vector.push_back(class_another_a);

 for (vector<ClassA*>::iterator it = test_vector.begin(); it != test_vector.end(); it++)
    it->printOutput();

The code retrieves the following error:

test3.cpp:47: error: request for member ‘printOutput’ in ‘* it.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator-> with _Iterator = ClassA**, _Container = std::vector >’, which is of non-class type ‘ClassA*’

The problem seems to be it->printOutput(); but at the moment I don't know how to call the method properly, does anyone know?

regards mikey

解决方案

The things in the vector are pointers. You need:

(*it)->printOutput();

which dereferences the iterator to get the pointer from the vector, then uses -> on the pointer to call the function. The syntax you show in your question would work if the vector contained objects rather than pointers, in which case the iterator acts like a pointer to one of those objects.

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