为啥会报无法解析的外部符号

Question

#include<iostream>
#pragma comment(lib,"ws2_64.lib")
using namespace std;
void main()
{
    void change1(int* x, int* y, int* z);
    int a, b, c;
    cout << "请输入三个数";
    cin >> a >> b >> c;
    change1(&a, &b, &c);
    cout << "a=" << a << "b=" << b << "c=" << c;

}

void change1(int& a, int& b, int& c)
{
    void change2(int&, int&);
    if (b > a)change2(a, b);
    if (c > a)change2(a, c);
    if (c > b)change2(c, b);
}
void change2(int& x, int& y)
{
    int    temp;
    temp = x;
    x = y;
    y = temp;
}

Answer 1

chang1函数的申明与函数体的参数类型不一致啊。