How can I overload = operator for 'MyClass object = f(x)'?












-2















As in title.
I have problem with operator overload.



int variable = 5;
int* f() {
return &variable;
}

class MyClass {
public:
int* i;
MyClass operator=(int* j) {
MyClass x;
x.i=j;
return x;
}
};


If I try to make my object like this:



MyClass m=f();


it doesn't work. But this:



MyClass m;
m=f();


works...










share|improve this question























  • Your operator() is creating a new MyClass and return it. You should mutate the current object.

    – Guillaume Racicot
    Jan 1 at 18:04











  • I modified it to: this->i=j; return *this;. Is it better now?

    – Filip Krawczyk
    Jan 1 at 18:10













  • @FilipKrawczyk Much better - it should also return by reference otherwise it's still a fresh object you're returning, which breaks chaining in subtle ways.

    – Lightness Races in Orbit
    Jan 1 at 20:14
















-2















As in title.
I have problem with operator overload.



int variable = 5;
int* f() {
return &variable;
}

class MyClass {
public:
int* i;
MyClass operator=(int* j) {
MyClass x;
x.i=j;
return x;
}
};


If I try to make my object like this:



MyClass m=f();


it doesn't work. But this:



MyClass m;
m=f();


works...










share|improve this question























  • Your operator() is creating a new MyClass and return it. You should mutate the current object.

    – Guillaume Racicot
    Jan 1 at 18:04











  • I modified it to: this->i=j; return *this;. Is it better now?

    – Filip Krawczyk
    Jan 1 at 18:10













  • @FilipKrawczyk Much better - it should also return by reference otherwise it's still a fresh object you're returning, which breaks chaining in subtle ways.

    – Lightness Races in Orbit
    Jan 1 at 20:14














-2












-2








-2








As in title.
I have problem with operator overload.



int variable = 5;
int* f() {
return &variable;
}

class MyClass {
public:
int* i;
MyClass operator=(int* j) {
MyClass x;
x.i=j;
return x;
}
};


If I try to make my object like this:



MyClass m=f();


it doesn't work. But this:



MyClass m;
m=f();


works...










share|improve this question














As in title.
I have problem with operator overload.



int variable = 5;
int* f() {
return &variable;
}

class MyClass {
public:
int* i;
MyClass operator=(int* j) {
MyClass x;
x.i=j;
return x;
}
};


If I try to make my object like this:



MyClass m=f();


it doesn't work. But this:



MyClass m;
m=f();


works...







c++






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Jan 1 at 17:52









Filip KrawczykFilip Krawczyk

31




31













  • Your operator() is creating a new MyClass and return it. You should mutate the current object.

    – Guillaume Racicot
    Jan 1 at 18:04











  • I modified it to: this->i=j; return *this;. Is it better now?

    – Filip Krawczyk
    Jan 1 at 18:10













  • @FilipKrawczyk Much better - it should also return by reference otherwise it's still a fresh object you're returning, which breaks chaining in subtle ways.

    – Lightness Races in Orbit
    Jan 1 at 20:14



















  • Your operator() is creating a new MyClass and return it. You should mutate the current object.

    – Guillaume Racicot
    Jan 1 at 18:04











  • I modified it to: this->i=j; return *this;. Is it better now?

    – Filip Krawczyk
    Jan 1 at 18:10













  • @FilipKrawczyk Much better - it should also return by reference otherwise it's still a fresh object you're returning, which breaks chaining in subtle ways.

    – Lightness Races in Orbit
    Jan 1 at 20:14

















Your operator() is creating a new MyClass and return it. You should mutate the current object.

– Guillaume Racicot
Jan 1 at 18:04





Your operator() is creating a new MyClass and return it. You should mutate the current object.

– Guillaume Racicot
Jan 1 at 18:04













I modified it to: this->i=j; return *this;. Is it better now?

– Filip Krawczyk
Jan 1 at 18:10







I modified it to: this->i=j; return *this;. Is it better now?

– Filip Krawczyk
Jan 1 at 18:10















@FilipKrawczyk Much better - it should also return by reference otherwise it's still a fresh object you're returning, which breaks chaining in subtle ways.

– Lightness Races in Orbit
Jan 1 at 20:14





@FilipKrawczyk Much better - it should also return by reference otherwise it's still a fresh object you're returning, which breaks chaining in subtle ways.

– Lightness Races in Orbit
Jan 1 at 20:14












1 Answer
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votes


















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That first example does not use operator= (yes, even though there is a = symbol!).



As it is a declaration/definition/initialization, it uses the constructor.



You may create a constructor to do what you need. This ought to be described in your C++ book.



By the way, your operator= is implemented weirdly. You're supposed to modify the current object, not create and return a new one. Again, refer to your book for the proper way of doing this.






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    1 Answer
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    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    1














    That first example does not use operator= (yes, even though there is a = symbol!).



    As it is a declaration/definition/initialization, it uses the constructor.



    You may create a constructor to do what you need. This ought to be described in your C++ book.



    By the way, your operator= is implemented weirdly. You're supposed to modify the current object, not create and return a new one. Again, refer to your book for the proper way of doing this.






    share|improve this answer




























      1














      That first example does not use operator= (yes, even though there is a = symbol!).



      As it is a declaration/definition/initialization, it uses the constructor.



      You may create a constructor to do what you need. This ought to be described in your C++ book.



      By the way, your operator= is implemented weirdly. You're supposed to modify the current object, not create and return a new one. Again, refer to your book for the proper way of doing this.






      share|improve this answer


























        1












        1








        1







        That first example does not use operator= (yes, even though there is a = symbol!).



        As it is a declaration/definition/initialization, it uses the constructor.



        You may create a constructor to do what you need. This ought to be described in your C++ book.



        By the way, your operator= is implemented weirdly. You're supposed to modify the current object, not create and return a new one. Again, refer to your book for the proper way of doing this.






        share|improve this answer













        That first example does not use operator= (yes, even though there is a = symbol!).



        As it is a declaration/definition/initialization, it uses the constructor.



        You may create a constructor to do what you need. This ought to be described in your C++ book.



        By the way, your operator= is implemented weirdly. You're supposed to modify the current object, not create and return a new one. Again, refer to your book for the proper way of doing this.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Jan 1 at 17:53









        Lightness Races in OrbitLightness Races in Orbit

        292k52475808




        292k52475808
































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