Same name for an argument and a local variable for the initialization function in GrainGrowth application.

[Xuesong Gao]

Hi, I am learning the grainGrowth application. In the file "ICs_and_BCs.cc", the initialization function "setInitialCondition(const dealii::Point<dim> &p, ...other arguments)" has an argument named p. Inside the function, there are also local variables named p.

// The big grains

{

dealii::Point<dim> p(0.2, 0.15);

center.push_back(p);

}I am confused why the argument p is used when referring to the coordinates.

dist += (p[dir] - center[index][dir] * userInputs.domain_size[dir]) *

(p[dir] - center[index][dir] * userInputs.domain_size[dir]);

Thanks.

[David Montiel]

Hello, Xuesong

In the lines within the setInitialCondition such as 

{dealii::Point<dim> p(0.2, 0.15); center.push_back(p);}

"p" is a new variable that is local to the scope defined by the curly braces {}. Even though it has the same name as the function argument (const dealii::Point<dim> &p), it is a separate variable that exists only within its block. In C++, variables declared in inner scopes (such as inside loops or blocks) can have the same name as those declared in outer scopes without causing conflicts. 

That being said, I think the name of the local variable should be changed to avoid confusion. I have opened issue #255 about this.

I hope this is helpful, 

David

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[Xuesong Gao]

David, much thanks!