I didn't know what this error means

[Bopaki]

The error is : New types may not be defined in

#include<iostream>
using namespace std;
 
class opOverClass
{
    friend ostream& operator<<(ostream&, const opOverClass&);
    friend istream& operator>>(istream&, opOverClass&);
public:
    opOverClass operator+(const opOverClass&)
;
   bool operator==(const opOverClass&) const;
    opOverClass(int i = 0, int j = 0);
private:
    int a;
    int b;
    }
opOverClass::opOverClass(int a, int b)
{
    a = 0;
    b = 0;
    }
opOverClass opOverClass::operator+
            (const opOverClass& right) const
{
    opOverClass temp;
    temp.a = a + right.a;
    temp.b = b + right.b;
    
    return temp;
}
bool opOverClass::operator==(const opOverClass& right) const
{
    return(a == right.a && b == right.b);
}
int main()
{
    opOverClass myClass(5, 6);
    cout << 5 + 6;
    }

  

[Bopaki]

New types may not be defined in a return type

[coder777]

Line 16: Missing ;.
Line 9/23: const doesn't match.

[Bopaki]

Thanks coder777 that semicolon helped a lot.
I am now dealing with new other errors now.

[AbstractionAnon]

Lines 6-7: Your operators are private. That's going to make them impossible to use outside your class.

Line 11: i and j are not members of your class.

Lines 19-20: You're setting the arguments to 0, not the class members. You probably want something like this:

opOverClass::opOverClass(int a_arg, int b_arg)
{   a = a_arg;
    b = b_arg;
}