Why does the compiler cannot pass?

[fl]

Hi,
I am compiling the following program below the dot line, which is copied from a website. There are some link errors:

1> overload_Arrow0.cpp
1>overload_Arrow0.obj : error LNK2019: unresolved external symbol "public: struct A * __thiscall B:perator->(void)" (??CB@@QAEPAUA@@XZ) referenced in function _main
1>overload_Arrow0.obj : error LNK2019: unresolved external symbol "public: struct B __thiscall C:perator->(void)" (??CC@@QAE?AUB@@XZ) referenced in function _main
1>overload_Arrow0.obj : error LNK2019: unresolved external symbol "public: struct C __thiscall D:perator->(void)" (??CD@@QAE?AUC@@XZ) referenced in function _main

I do not solve this after several trials. What is wrong with the code?

Thanks a lot.

.......
#include <iostream>


struct A {
void foo();
};

void A::foo()
{
;
}


struct B { A* operator->(); };
struct C { B operator->(); };
struct D { C operator->(); };

int main()
{
D d;
d->foo();
}

 

[Victor Bazarov]

Hi,
I am compiling the following program below the dot line, which is copied from a website. There are some link errors:

1> overload_Arrow0.cpp
1>overload_Arrow0.obj : error LNK2019: unresolved external symbol "public: struct A * __thiscall B:perator->(void)" (??CB@@QAEPAUA@@XZ) referenced in function _main
1>overload_Arrow0.obj : error LNK2019: unresolved external symbol "public: struct B __thiscall C:perator->(void)" (??CC@@QAE?AUB@@XZ) referenced in function _main
1>overload_Arrow0.obj : error LNK2019: unresolved external symbol "public: struct C __thiscall D:perator->(void)" (??CD@@QAE?AUC@@XZ) referenced in function _main

I do not solve this after several trials. What is wrong with the code?

Just like your linker tells you, it cannot find those functions.

Thanks a lot.

......
#include <iostream>


struct A {
void foo();
};

void A::foo()
{
;
}


struct B { A* operator->(); };
struct C { B operator->(); };
struct D { C operator->(); };

The three lines above define classes B, C, D, respectively, and each of
those classes *declares* operator->() function, but there is no
*definition* of those functions (B:perator->, etc.) in your code. You
should consider defining them since you actually call those in your
'main' program.

int main()
{
D d;
d->foo();
}

V