#include <iostream>
using namespace std;
class A{
public:
    A(char* par){cout << "A::A" << endl;}
    A(const A& other){cout << "copy" << endl;}
    A& operator=(const A& other){cout << "operator =" << endl;}
};

void test(char* a){ 
    cout << "test==>char*" << endl;
}

void test(const A& a){ 
    cout << "test==>const A&" << endl;
}

int main()
{
    char* str = "gg";
    test(str);//呼叫void test(char* a)

    test(A(str));//呼叫void test(const A& a)
    return 0;
}
 

================================

-->若函式void  test(const A& a)定義為const test(A& a), 則test("hh")呼叫會失敗，引用型別初始化錯誤

(invalid initialization of reference of type ‘A&’ from expression of type ‘char*’)