通过引用传递向量 [英] Passing vector by reference

问题描述

使用正常的C数组我会这样做：

Using normal C arrays I'd do something like that:

void do_something(int el, int **arr)
{
   *arr[0] = el;
   // do something else
}

现在，数组与向量，并在此实现相同的结果：

Now, I want to replace standard array with vector, and achieve the same results here:

void do_something(int el, std::vector<int> **arr)
{
   *arr.push_front(el); // this is what the function above does
}

但它显示类类型。如何正确地这样做？

But it displays "expression must have class type". How to do this properly?

推荐答案

您可以通过引用传递容器，以便在函数中修改它。还没有解决的其他答案是 std :: vector 没有成员函数 push_front 。您可以在向量上使用 insert（）成员函数进行O（n）插入：

You can pass the container by reference in order to modify it in the function. What other answers haven’t addressed is that std::vector does not have a push_front member function. You can use the insert() member function on vector for O(n) insertion:

void do_something(int el, std::vector<int> &arr){
    arr.insert(arr.begin(), el);
}

或使用 std :: deque 代替分摊的O（1）插入：

Or use std::deque instead for amortised O(1) insertion:

void do_something(int el, std::deque<int> &arr){
    arr.push_front(el);
}

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