汉诺塔小程序执行的问题

#include <iostream>
using namespace std;
void move(char no1,char no2)
{
    cout<<no1<<"移动到"<<no2<<endl;
}
void hannoi(int n,char n1,char n2,char n3)
{
    if(n==1)
        move (n1,n3);
    else
    {
        hannoi(n-1,n1,n3,n2);
        move(n1,n3);
        hannoi(n-1,n2,n1,n3);
    }
}
int main()
{
    void hanoi(int n,char n1,char n2,char n3);
    int m;
    cout<<"请输入A柱上金盘的总数:";
    cin>>m;
    cout<<"当有"<<m<<"个金盘时，移动的步骤依次为:"<<endl;
    hanoi(m,'A','B','C');
    return 0;
}

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执行的时候出现了错误
汉诺塔.obj : error LNK2001: unresolved external symbol "void __cdecl hanoi(int,char,char,char)" (?hanoi@@YAXHDDD@Z)
Debug/汉诺塔.exe : fatal error LNK1120: 1 unresolved externals


什么意思啊，要怎么改，帮忙下