# Operators
This chart shows the operators that can be overloaded.
4 operators cannot be overloaded:
::(scope resolution),.(member access),.*(member access through pointer to member),?:(ternary conditional)
# Rule
运算符函数的名称是以关键字operator为前缀的.
e.g. We need our + operator to return a new MyClass object with a member variable equal to the sum of the two objects' member variables.
class MyClass {
public:
int var;
MyClass();
MyClass(int a): var(a) {}
MyClass operator+(MyClass &obj) {
MyClass res;
res.var= this->var + obj.var;
return res;
}
};
int main() {
MyClass obj1(12), obj2(55);
MyClass res = obj1 + obj2;
cout << res.var;
return 0;
}
# ooo
通过运算符重载，只能改变运算符原有的操作数类型(而不是优先级, 操作数个数).
成员函数是否:
有的运算符只能作为成员函数重载 (定义为非成员函数时, 会编译错误):
赋值
=, 下标[], 调用(), 指针的成员访问-＞, 所有的类型转换运算符.有些运算符函数不能定义为类的成员函数，如I/O操作符
有的运算符可以作为非成员函数重载: 算术运算符、相等运算符
++x等效的运算符函数调用形式为x.operator++()