按引用传递 - C++:合并排序 问题:超出范围

（C++）大家好，这是我第一次尝试合并排序。我看到我的代码类似于之前发布过问题的人：这里。在较低级别，排序按预期工作。但是，我相信我在这里的问题是排序数组在每个较低级别之后都超出了范围，因此从未正确排序。在这种情况下，我尝试使用"std：：vector&"通过引用传递。我错了吗？通过引用的正确方法是什么？

下面是我的代码：

/*
MERGE SORT
breaking down the sorting into pairs concursively until we are comparing only two values
The two integers parameters denotes indices for beginning and ending values in vector
Merge sort inclusive of both left and right range
*/
#include <vector> // for using vectors in c++
void merge(std::vector<int>& inputv, int beg_i, int end_i)
{
    int d = beg_i;  // used as an index
    int e = beg_i + (end_i - beg_i)/2 + 1;  // used as an index
    int y = beg_i + (end_i - beg_i)/2;     // used as a check against d
    int z = end_i;  // used as a check against e
    std::vector<int> tempvect(inputv.size());
    for (int c = beg_i; c < z+1; c++)
    {
        if (e > z && d > y)
        {
            // do nothing
        }
        else if (e > z)
        {
            tempvect[c] = inputv[d];
            d++;
        }
        else if (d > y)
        {
            tempvect[c] = inputv[e];
            e++;
        }
        else if(inputv[d] > inputv[e])
        {
            tempvect[c] = inputv[e];
            e++;
        }
        else if(inputv[d] <= inputv[e])
        {
            tempvect[c] = inputv[d];
            d++;
        }
    }
    for (int i = beg_i; i < end_i+1; i++)
    {
        inputv[i] = tempvect[i];
    }
}
void mergesort(std::vector<int> inputvector, int beg_i, int end_i)
{
    if(end_i - beg_i == 0) 
    {
        // do nothing
    }
    if(end_i - beg_i >= 1)
    {
        int mid_i = beg_i + (end_i - beg_i)/2;
        mergesort(inputvector,beg_i,mid_i); // reclusive to last card
        mergesort(inputvector,mid_i+1,end_i);   // resulsive to last card
        merge(inputvector,beg_i,end_i); // actual implementation to sort and merge the vectors
    }
}