求助，实现合并array重复元素

rt，要实现一合并两个数组的重复元素，上面方法返回指针，在返回之前输出测试是对的。但是到main里赋值给final之后，final只占8个字节（2个元素）就不对了。而且如果把main中的循环次数改为final本该有的长度，就可以正确输出。是怎么回事呢？代码和运行如下

怎么会这么糊啊

#include <iostream>
#define LEN_A 5
#define LEN_B 6
using namespace std;
int* union_Array (int a[], int lenA, int b[], int lenB)
{
int len_temp = lenA + lenB;
int *temp = new int [len_temp];
cout << len_temp << endl;//test
for (int m = 0; m < lenA; m++)
temp [m] = a [m];
for (int n = 0; n < lenB; n++)
temp [n + lenA] = b[n];
int i,j,k = 0;
for (i = 0; i < len_temp; i++)
{
for (j = i + 1; j < len_temp; j++)
{
if (temp [j] == temp [i])
{
for (k = j + 1; k < len_temp; k++)
{
temp [k-1] = temp [k];
}
len_temp --;
cout << len_temp << " ";//test
j --;
}
}
}//去除重复
cout << "\nfinal: "<< len_temp << endl;//test
for (int l = 0; l < len_temp; l++)
cout << temp[l] << " ";
return temp;
}
int main()
{
int a[] = {1,2,3,4,50};//test
int b[] = {1,2,3,4,5,66};//test
int *final = union_Array(a, LEN_A, b, LEN_B);
cout << '\n' << sizeof(a) / sizeof(a[0]) << " a\n";//test
cout << sizeof(final) / sizeof(final[0]) << " final\n";//test
for (int i = 0; i < sizeof(final); i++)
cout << final[i] << " ";
delete[] final;
return 0;
}