如何在 C + + 中迭代对象列表？

我是 C + + 的新手，正在努力弄清楚我应该如何迭代一个对象列表并访问它们的成员。

我一直在尝试这种情况下，data是一个 std::list和 Student一个类。

std::list<Student>::iterator<Student> it;
for (it = data.begin(); it != data.end(); ++it) {
std::cout<<(*it)->name;
}

并得到以下错误:

error: base operand of ‘->’ has non-pointer type ‘Student’
291270 次浏览
小开

-> it works like pointer u don't have to use *

for( list<student>::iterator iter= data.begin(); iter != data.end(); iter++ )
cout<<iter->name; //'iter' not 'it'
小开
最佳答案

You're close.

std::list<Student>::iterator it;
for (it = data.begin(); it != data.end(); ++it){
std::cout << it->name;
}

Note that you can define it inside the for loop:

for (std::list<Student>::iterator it = data.begin(); it != data.end(); ++it){
std::cout << it->name;
}

And if you are using C++11 then you can use a range-based for loop instead:

for (auto const& i : data) {
std::cout << i.name;
}

Here auto automatically deduces the correct type. You could have written Student const& i instead.

小开

It is also worth to mention, that if you DO NOT intent to modify the values of the list, it is possible (and better) to use the const_iterator, as follows:

for (std::list<Student>::const_iterator it = data.begin(); it != data.end(); ++it){
// do whatever you wish but don't modify the list elements
std::cout << it->name;
}
小开

Since C++ 11, you could do the following:

for(const auto& student : data)
{
std::cout << student.name << std::endl;
}
小开

if you add an #include <algorithm> then you can use the for_each function and a lambda function like so:

for_each(data.begin(), data.end(), [](Student *it)
{
std::cout<<it->name;
});

you can read more about the algorithm library at https://en.cppreference.com/w/cpp/algorithm

and about lambda functions in cpp at https://learn.microsoft.com/en-us/cpp/cpp/lambda-expressions-in-cpp?view=vs-2019


提交答案