Static variables inside member functions

[Azdo]

Hello,

if I code something like this,

class A{
void f(){
static i=0;
}};

int main(){
A a1,a2;

return 0;
}

will a1::f::i and a2::f::i be identical?

TIA!

 

[Suman]

Hello,

if I code something like this,

class A{

//calling f() later is a pain otherwise
public:

void f(){
static i=0;

i++;
std::cout<<i<<std::endl;

}};

int main(){
A a1,a2;

a1.f();
a2.f();

return 0;
}

will a1::f::i and a2::f::i be identical?

TIA!

Run the code, and you will know!

 

[Azdo]

Suman ha escrito:

//calling f() later is a pain otherwise
public:

Sorry, I forgot about that.

Run the code, and you will know!

Yes, but if I run the code, I could not say from the results if it is
the expected behaviour or the compiler is wrong.

Thank you anyway

 

[Jaspreet]

Hello,

if I code something like this,

class A{
void f(){
static i=0;
}};

int main(){
A a1,a2;

return 0;
}

will a1::f::i and a2::f::i be identical?

TIA!

Assuming you have your public and private scope written correctly.

Yes the static data members are sharable among different instances of
the class. Soo, if a1 modifies i that changed value woudl be reflected
when i is accessed using a2.

 

[Azdo]

Jaspreet ha escrito:

Assuming you have your public and private scope written correctly.

Yes, my fault.

Yes the static data members are sharable among different instances of
the class. Soo, if a1 modifies i that changed value woudl be reflected
when i is accessed using a2.

The difference here is that 'i' is not a static member of the class but
a static variable of a function (which happens to be a function
member). I don't know if we can consider 'i' a member of the class, can
we?

Thank you.

 

[Jaspreet]

Jaspreet ha escrito:

Yes, my fault.


The difference here is that 'i' is not a static member of the class but
a static variable of a function (which happens to be a function
member). I don't know if we can consider 'i' a member of the class, can
we?

Oops. I apologise for that. Did not really notice that. Yes i is a
static variable for a function and cannot be termed as a static
variable of the class. Coming to your original question , yes i will be
same if you access it from a1 or a2. As long as you are in the program
i will continue to be available.

BTW, ** static i=0; ** is deprecated since you need to explicitly give
the data-type.

 

[Howard]

Hello,

if I code something like this,

class A{
void f(){
static i=0;
}};

int main(){
A a1,a2;

return 0;
}

will a1::f::i and a2::f::i be identical?

Yes, they will be the same, because f is the same. Member functions are
shared among instances of the class. There is not one f for each instance
of A. So, any static variables in f will be identical for all instances of
A (within a given process).

-Howard