CODEWITHSUNDEEP
c++
Aman
Aman

Reputation: 73

UserDefined Comparison Operator (operator> , operator< etc)

I'm new to Userdefined Comparison Operator. I was reading a book where the following example is mentioned :

struct P { 
           int x, y;
           bool operator<(const P &p) { 
                 if (x != p.x)
                   return x < p.x;
                 else 
                   return y < p.y; } 
         };

I want to understand bool operator<(const P &p). Particularly i understand that bool is the return type of the operator i.e. return value is either true or false.

But I am confused , what is the significance of < in operator< and how does this operator is actually working? What values are being compared?

Upvotes: 0

Views: 431

Answers (2)

Destiny
Destiny

Reputation: 506

P a, b;
bool ret = a < b;

It actually is:

P a, b;
bool ret = a.operator<(b);  // And < in operator<:  x.operator<(p.x)

Did this help you to a better understanding?

Upvotes: 1

Kilbo
Kilbo

Reputation: 365

So you have a struct with two integers. X and Y. What the code above is saying is if X in the struct you're in (also known as "this") is not equal to the x in the struct passed in (p) then do a regular less than comparison between x and p's x. If they are equal, then compare the y of this to p's y.

The significance of "<" in "operator<" is to let the compiler know you're overloading the "<" operator allowing you to use it to compare to structs of type P. If you don't overload the < operator for a custom type you cannot use it to compare two of those objects.

Upvotes: 0

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