Question

For checking equality in a simple array, i’ve the following;

int a[4] = {9,10,11,20};
    if(a[3]== 20){
        cout <<"yes"<< endl;
    }

However, when I create an array of type class, and try and check equality I get error;

Human is a class with private variables for name, age, gender etc, and
get and set functions for these variables.

humanArray has size 20

void Animal::allocate(Human h){
    for (int i =0; i<20; i++){
        if(humanArray[i] == h){
            for(int j = i; j<size; j++){
                humanArray[j] = humanArray[j +1];
            }
        }
    }
}

I get following error;

error: no match for 'operator==' in '((Animal*)this)->Animal::humanArray[i] == h'|

I could pass in the index and Human, and check against index number. However, is there a way to check if two elements are same? I don’t wish to check say ‘Human name’ against human name, since for some parts my human will not have a name.

Answer 1

In order to make the syntax

if(humanArray[i] == h)

legal, you will need to define operator== for your human class. To do this, you might write a function that looks like this:

bool operator== (const Human& lhs, const Human& rhs) {
   /* ... */
}

Inside this function, you would do a field-by-field comparison of lhs and rhs to see if they were equal. From this point forward, any time that you try to compare any two humans by using the == operator, C++ will automatically call this function for you to make the comparison.

Hope this helps!