C++出現 error: no match for 'operator==' (operand types are 'Person' and 'const Person')

前提：

用內置函數對象find測試查找自定義數據類型Person

代碼：

class Person{
public:
    string m_Name;
    int m_Age;
    Person(string name, int age)
    {
        this->m_Name = name;
        this->m_Age = age;
    }
};
void test01(void)
{
    vector<int> vec1;
    for(int i = 0; i < 10; i++)
    {
        vec1.push_back(i + 3);
    }
    //查找內置數據類型
    vector<int>::iterator pos1 = find(vec1.begin(), vec1.end(), 9);
    cout << *pos1 << endl;
    //查找自定義數據類型
    vector<Person> vec2;
    Person p1("aaa", 10);
    Person p2("bbb", 20);
    Person p3("ccc", 30);
    Person p4("ddd", 40);
    vec2.push_back(p1);
    vec2.push_back(p2);
    vec2.push_back(p3);
    vec2.push_back(p4);
    vector<Person>::iterator pos2 = find(vec2.begin(), vec2.end(), p1);
    cout << (*pos2).m_Name << " " << (*pos2).m_Age << endl;

}
int main(void)
{
    test01();
    system("pause");
    return 0;
}

錯誤：

D:\software\destination\Qt5.6.1\Tools\mingw492_32\i686-w64-mingw32\include\c++\bits\predefined_ops.h:191: error: no match for 'operator==' (operand types are 'Person' and 'const Person')
  { return *__it == _M_value; }
                 ^

 

分析：

error: no match for 'operator=='沒有匹配的==判斷函數，說明編譯器不知道Person類怎么比較算是兩個對象相等

 

解決：

在Person類中重載==運算符

class Person{
public:
    string m_Name;
    int m_Age;
    Person(string name, int age)
    {
        this->m_Name = name;
        this->m_Age = age;
    }
    bool operator ==(const Person& p)
    {
        return (this->m_Name == p.m_Name) && (this->m_Age == p.m_Age);
    }
};