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Why does this work?

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•

Join Date: Apr 2008

Posts: 10

Reputation: n3XusSLO is an unknown quantity at this point

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n3XusSLO

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Newbie Poster

Why does this work?

Nov 13th, 2008

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
std::string s="s1";
std::cout<<s<<std::endl;
{
	std::string s="s2";
	std::cout<<s<<std::endl;
};
std::string s="s1";
std::cout<<s<<std::endl;
{
	std::string s="s2";
	std::cout<<s<<std::endl;
};

Why can I have two variables with the same name existing like this?

•

Join Date: Dec 2007

Posts: 68

Reputation: Rhohitman is an unknown quantity at this point

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Rhohitman

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Re: Why does this work?

Nov 13th, 2008

it is becoz of the scope of the variable
one declare out side the function is in the Global Scope
and other one is inside the Function having the Function Scope
...
now how question is if the variable name is same then... how does it works...
Answer is ...
by help of scope operator(i am not sure it is operator or not sorry to say i forgot) "::"
if the variable is in the global scope the ::<variable>
if there is no ambiguity in the name of the variable then the scope resolution operator is not need ...

this thing comes handy in class..

Chazing Dreams ;'P
Shhhh.......ZZzzzzzzzzzzzzzzzzzzzz.....

•

Join Date: Apr 2008

Posts: 10

Reputation: n3XusSLO is an unknown quantity at this point

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n3XusSLO

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Re: Why does this work?

Nov 13th, 2008

thanks

•

Join Date: Jul 2005

Posts: 1,675

Reputation: Lerner is a name known to all

Solved Threads: 261

Lerner

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Posting Virtuoso

Re: Why does this work?

Nov 13th, 2008

Where's the function? Wouldn't the {}s be ignored since there is no function or if statement or control loop associated with the {}s to generate a new scope?

Klatu Barada Nikto

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Join Date: Sep 2008

Posts: 273

Reputation: Sci@phy will become famous soon enough

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Sci@phy

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Re: Why does this work?

Nov 13th, 2008

AFAIK brackets can be used without any function or if statement, simply as code-block.
They just come in handy for functions, classes, etc.

•

Join Date: Dec 2007

Posts: 68

Reputation: Rhohitman is an unknown quantity at this point

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Rhohitman

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Re: Why does this work?

Nov 13th, 2008

•

Originally Posted by Lerner

Where's the function? Wouldn't the {}s be ignored since there is no function or if statement or control loop associated with the {}s to generate a new scope?

ya ya, thanx for correcting...

Chazing Dreams ;'P
Shhhh.......ZZzzzzzzzzzzzzzzzzzzzz.....

•

Join Date: Jul 2005

Posts: 1,675

Reputation: Lerner is a name known to all

Solved Threads: 261

Lerner

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Posting Virtuoso

Re: Why does this work?

Nov 13th, 2008

>>AFAIK brackets can be used without any function or if statement, simply as code-block.
They just come in handy for functions, classes, etc.

That would be interesting.

Klatu Barada Nikto

•

Join Date: Sep 2008

Posts: 273

Reputation: Sci@phy will become famous soon enough

Solved Threads: 42

Sci@phy

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Posting Whiz in Training

Re: Why does this work?

Nov 13th, 2008

•

Originally Posted by Lerner

>>AFAIK brackets can be used without any function or if statement, simply as code-block.
They just come in handy for functions, classes, etc.

That would be interesting.

I'm stunned. Can somebody tell me if bracket section alone is by C/C++ standard?
Because, DevC++ mingw and Visual C++ Express 2008 both compile and execute properly:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
 
int main(){
    int a=5;
    std::cout<<"Out of bracket:"<<a;
    {
        int a = 6;
        std::cout<<"\nIn bracket: "<<a;
    }
    std::cout<<"\nOut again: "<<a<<std::endl;
 
    std::cin.get();
    return 0;
}
#include <iostream>

int main(){
    int a=5;
    std::cout<<"Out of bracket:"<<a;
    {
        int a = 6;
        std::cout<<"\nIn bracket: "<<a;
    }
    std::cout<<"\nOut again: "<<a<<std::endl;
    
    std::cin.get();
    return 0;
}

Providing output:

•

Out of bracket: 5
In bracket: 6
Out again: 5

•

Join Date: Jul 2005

Posts: 1,675

Reputation: Lerner is a name known to all

Solved Threads: 261

Lerner

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Posting Virtuoso

Re: Why does this work?

Nov 13th, 2008

Maybe it's one of those things like it's valid to use OR instead of || or AND instead of &&, or that a comma is an operator, etc. But, yeah, it would be interesting if those who have access to a copy of the standard or know the relevant section of the standard would post a report.

Klatu Barada Nikto