C++ 试图交换向量中的值
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C++ trying to swap values in a vector
提问by user782311
This is my swap function:
这是我的交换功能：
template <typename t>
void swap (t& x, t& y)
{
t temp = x;
x = y;
y = temp;
return;
}
And this is my function (on a side note v stores strings) call to swap values but whenever I try to call using values in a vector I get an error. I'm not sure what I'm doing wrong.
这是我的函数（在旁注中 v 存储字符串）调用交换值，但是每当我尝试使用向量中的值调用时，我都会收到错误消息。我不确定我做错了什么。
swap(v[position], v[nextposition]); //creates errors
回答by Moha the almighty camel
I think what you are looking for is iter_swapwhich you can find also in <algorithm>.
all you need to do is just pass two iterators each pointing at one of the elements you want to exchange.
since you have the position of the two elements, you can do something like this:
我认为您正在寻找的是iter_swap您也可以在 <algorithm>.
您需要做的就是传递两个迭代器，每个迭代器都指向您要交换的元素之一。
由于您拥有两个元素的位置，因此您可以执行以下操作：
// assuming your vector is called v
iter_swap(v.begin() + position, v.begin() + next_position);
// position, next_position are the indices of the elements you want to swap
回答by linse
Both proposed possibilities (std::swapand std::iter_swap) work, they just have a slightly different syntax.
Let's swap a vector's first and second element, v[0]and v[1].
两种提议的可能性 (std::swap和std::iter_swap) 都有效，只是语法略有不同。让我们交换一个向量的第一个和第二个元素，v[0]和v[1]。
We can swap based on the objects contents:
我们可以根据对象内容进行交换：
std::swap(v[0],v[1]);
Or swap based on the underlying iterator:
或者基于底层迭代器进行交换：
std::iter_swap(v.begin(),v.begin()+1);
Try it:
尝试一下：
int main() {
int arr[] = {1,2,3,4,5,6,7,8,9};
std::vector<int> * v = new std::vector<int>(arr, arr + sizeof(arr) / sizeof(arr[0]));
// put one of the above swap lines here
// ..
for (std::vector<int>::iterator i=v->begin(); i!=v->end(); i++)
std::cout << *i << " ";
std::cout << std::endl;
}
Both times you get the first two elements swapped:
两次交换前两个元素：
2 1 3 4 5 6 7 8 9
回答by faro_hf
after passing the vector by reference
通过引用传递向量后
swap(vector[position],vector[otherPosition]);
will produce the expected result.
将产生预期的结果。
