call copy constructor in "=" operator

[fourfires.d]

Dear All,

I am new to c++ and when write below code that try to call copy
constructor
in "=" operator overloading, it can not compile. Can anyone point out
for
me the reason? thanks !!

class AA
{
public:

AA( AA & obj)
{
}

AA & operator=( AA & obj)
{
AA(obj);
return *this;
}

};

int main()
{

return 0;
}

pp.cc: In method `class AA & AA::operator =(AA &)':
pp.cc:11: declaration of `obj' shadows a parameter
pp.cc:11: no matching function for call to `AA::AA ()'
pp.cc:6: candidates are: AA::AA(AA &)

[Old Wolf]

dc wrote:

This is quite strange

Suppose AA has a constructor with arg int.
int inst;
........
AA (inst);//Treats inst as a variable of AA.
AA(10);//OK

The rule is: If it could compile OK as a declaration, then it is;
otherwise it isn't. :) Here's another example:

typedef int x;
class A { };

void foo()
{
A b(x); // declares function b taking int as parameter
// and returning an A (!)

A (x); // declares local variable named 'x'
// (hides the typedef)
A a(x); // creates object 'a' , passing local variable
// 'x' to its copy constructor

}

[Alf P. Steinbach]

* Old Wolf:

dc wrote:

This is quite strange

Suppose AA has a constructor with arg int.
int inst;
........
AA (inst);//Treats inst as a variable of AA.
AA(10);//OK

The rule is: If it could compile OK as a declaration, then it is;
otherwise it isn't. :) Here's another example:

typedef int x;
class A { };

void foo()
{
A b(x); // declares function b taking int as parameter
// and returning an A (!)

A (x); // declares local variable named 'x'
// (hides the typedef)
A a(x); // creates object 'a' , passing local variable
// 'x' to its copy constructor

}

He he... :-) :-) :-)

The description "failed experiment" is very apt.

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