operator overload notes

1. []Overload

• For ordinary arrays, the following two writing methods have the same effect:

a[2]
2[a]
Is the third one to access the a array

• For access to the internal array of the object, only the first method can be used. Here there are two types of return values: numeric and reference. If you want to make a numeric element an lvalue, you must use a reference return value.

// 一维数组访问
int& operator [](int index){
    
    
	if(index > 0 && index < length){
    
    
		return v[index];
	}else{
    
    
		//越界特殊处理
	}
}

// 二维数组访问，这里分行、列来两次访问
int* operator [](int index){
    
    
	if(index > 0 && index < length){
    
    
		// 返回某行指针
		return array[index];
	}else{
    
    
		//越界处理
	}
}

2. Use operator for type conversion (here are member functions)

• Class type conversion to standard type

operator int(){
    
    
	//代码块
}

• Conversion between class types

operator className(){
    
    
	//代码块
}

• Note: The function has no return value, but you can write the return value inside the code.