Why is the output is coming out to be zero for my friend operation overloaded code

Question

When I am trying to run this code I am getting the output to be zero which isn't expected, according to what I have defined I should get a -1 rather than a 0,I have tried changing the values of x,I have tried looking up for the garbage value if any. What you guys think?

#include<iostream>
using namespace std;

class nf {
    int x;
public:
    nf() {
        x=1;
    }
    nf(int a) {
        a=x;
    }

    friend nf operator ++(nf n1) {
        n1.x=-n1.x;
    }
    void display() {
        cout<<x;
    }
};

int main()
{
    nf obj(1),obj2;
    obj2=++obj;
    obj2.display();
}

See [this](http://stackoverflow.com/questions/4421706/operator-overloading) for the correct way to overload operators. — NathanOliver, Mar 06 '17 at 19:41
Well, I think that the TAB key on your keyboard appears to be broken, with the resulting code being somewhat unreadable, and hard to follow. You might wish to get your keyboard replaced, so that it's possible for you to cleanly, logically indent your code to make it readable to other people. — Sam Varshavchik, Mar 06 '17 at 19:41
@iCas I don't know what you did to change the alignment, but it didn't work. — George, Mar 06 '17 at 19:44
@George The syntax and code seems fine it should work but no clue what went wrong. — Saubhagya, Mar 06 '17 at 19:45
Write the operator the right way like it shows in the Q&A I linked to. — NathanOliver, Mar 06 '17 at 19:47
Also, looks like `a=x;` should be `x=a;` or better yet `nf(int a) : x(a) { }` — George, Mar 06 '17 at 19:50
@NathanOliver I just saw the Q/A but i am not able to diagnose the error suggestions please? — Saubhagya, Mar 06 '17 at 19:51
@George Tried changing that but didn't work. The overloading of function isn't giving the desired output. — Saubhagya, Mar 06 '17 at 19:56

score 0 · Accepted Answer · answered Mar 06 '17 at 19:59

0

Sorted.

#include<iostream>
using namespace std;
class nf{
    int x;
    public:
    nf()
    {
        x=1;
    }
    nf(int a){
        x=a;
    }
friend nf operator ++(nf &n1)
{
    n1.x=-n1.x;
}
void display()
{
    cout<<x;
}



};
int main()
{
 nf c1;
 ++c1;
 c1.display();

}

answered Mar 06 '17 at 19:59

Saubhagya

155
12

`friend nf operator ++(nf &n1){ n1.x=-n1.x;}` -- Undefined behavior. An `nf` is supposed to be returned, but nothing is returned. – PaulMcKenzie Mar 06 '17 at 20:40

Why is the output is coming out to be zero for my friend operation overloaded code

1 Answers1