合并排序在C++

#include "stdafx.h"
#include <iostream>
using namespace std;
using namespace System;
void mergesort(int a[], int p, int r);
void merge(int a[], int p, int q, int r);
int main(array<System::String ^> ^args)
{
    int result[2] = { 1, 0 };
    int *p;
    p = result;
    mergesort(p, 0,1);
    while (1);
    return 0;
}
void mergesort(int a[],int p, int r)
{
    if (p < r)
    {
        int q = (p + r) / 2;
        mergesort(a, p, q);
        cout << endl;
        mergesort(a, q + 1, r);
        cout << endl;
        merge(a,p,q,r);
        for (int i = 0; i < 2; i++)
        {
            cout << a[i] << " ";
        }
        cout << endl;
    }
}
void merge(int a[], int p, int q, int r)
{
    int left[100] = {};
    int right[100] = {};
    for (int i = 0; i < (q - p + 1); i++)
    {
        left[i] = *(a + p + i);
        left[i + 1] = 999;
    }
    for (int i = 0; i < (r - q); i++)
    {
        right[i] = *(a + q + 1 + i);
        right[i + 1] = 999;
    }
    for (int k = p; k < r+1; k++)
    {
        int i = 0;
        int j = 0;
        if (left[i] <= right[j])
        {
            a[k] = left[i++];
        }
        else
        {
            a[k] = right[j++];      **// it always goes into this route? why does not left[i]<=right[j] work?**
        }
    }
}

这是我关于基本合并排序的代码。我无法在合并函数中输入第一个 IF 语句。为什么if (left[i] <= right[j])不起作用？我试过了，无论left[i]是什么。程序只是转到 else 语句。