Object Initialization in C++

[Venkat]

Hello All.

I am having a trouble creating a Object in Case Label, and calling the
Member Function outside the Switch. Can some one please help me..??

My code looks like

int main()
{
int number;
cout <<"1. Chevy"<<endl;
cout << "2. Toyota"<<endl;
cout << "enter a number"<<endl;
cin >> number;
switch(number)
{
case 1:
{
Chevy o;
}
break;
case 2:
{
Toyota o;
}
break;
default:
{
Auto o;
}
break;
}
o.Description();
return 0;
}


In this case I want to call the Description Member Function depending
on the Object.

But the Compiler does not know about "o". How can I implement this.??


Thanks in advance
-Venkat

 

[tom_usenet]

Hello All.

I am having a trouble creating a Object in Case Label, and calling the
Member Function outside the Switch. Can some one please help me..??

Once an automatic object has gone out of scope, it no longer exists,
so you can't possibly call member functions of it.

My code looks like

What about Chevy, etc.? Do they all derive from Auto?

int main()
{
int number;
cout <<"1. Chevy"<<endl;
cout << "2. Toyota"<<endl;
cout << "enter a number"<<endl;
cin >> number;
switch(number)
{
case 1:
{
Chevy o;
}
break;
case 2:
{
Toyota o;
}
break;
default:
{
Auto o;
}
break;
}
o.Description();
return 0;

Instead:

int number;
cout <<"1. Chevy"<<endl;
cout << "2. Toyota"<<endl;
cout << "enter a number"<<endl;
cin >> number;
Auto* o = 0;
switch(number)
{
case 1:
{
o = new Chevy;
}
break;
case 2:
{
o = new Toyota;
}
break;
default:
{
o = new Auto;
}
break;
}
o->Description();
delete o;
return 0;
}

In this case I want to call the Description Member Function depending
on the Object.

But the Compiler does not know about "o". How can I implement this.??

Using polymorphism. Auto should look like this:

class Auto
{
public:
virtual ~Auto();
virtual void Description();
};

And the others should override Description.

Tom

 

[Josephine Schafer]

Hello All.

I am having a trouble creating a Object in Case Label, and calling the
Member Function outside the Switch. Can some one please help me..??

My code looks like

int main()
{
int number;
cout <<"1. Chevy"<<endl;
cout << "2. Toyota"<<endl;
cout << "enter a number"<<endl;
cin >> number;
switch(number)
{
case 1:
{
Chevy o;
}
break;
case 2:
{
Toyota o;
}
break;
default:
{
Auto o;
}
break;
}
o.Description();
return 0;
}


In this case I want to call the Description Member Function depending
on the Object.

But the Compiler does not know about "o". How can I implement this.??

A simple way would be to declare a base class Vehicle.
Derive Chevy, Toyota and Auto from it.
Declare Description to be a virtual function in Vehicle.
Then declare Vehicle *p = NULL;
.....
{
case 1:
p = new Chevy;
case 2:
//
case 3:
// so on ..
}
// then call description
p ->Description ();
delete p;

Don't forget to declare the destructor in Vehicle class to be virtual.

HTH,
J.Schafer

 

[David Rubin]

Hello All.

I am having a trouble creating a Object in Case Label, and calling the
Member Function outside the Switch. Can some one please help me..??
[snip]
switch(number)
{
case 1:
{
Chevy o;
}

What is the scope of o in the above example?

In any case, a more correct solution has been given.

/david

 

[red floyd]

Hello All. [switch statement from hell redacted]

[simple and lucid explanation and solution redacted]

Don't forget to declare the destructor in Vehicle class to be virtual.

He should also look into the Factory pattern.