Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

argument of a function

Posted on 2003-11-12
2
Medium Priority
?
233 Views
Last Modified: 2010-04-01
To C++ experts,

 I have a code as follows :
--------------------------------------------------------------
class A{} ;
class B
{   public :
      void f(A const& a){ cout << "f" << endl ;}
      void g(A const&){ cout << "g" << endl ;}
};

int main()
{
  A a1 ;
  B b1 ;
  b1.f(a1) ;
  b1.g(a1) ;
  return 0 ;
}
---------------------------------------------
  It seems that both f(A const& a) and g(A const&) work. However, I am wondering is there any difference between them ? which one is better and which one should I use in general ?

  Thanks a lot !

meow.
 
0
Comment
Question by:meow00
2 Comments
 
LVL 30

Accepted Solution

by:
Axter earned 120 total points
ID: 9737659
>>It seems that both f(A const& a) and g(A const&) work. However, I am wondering is there any difference between them ? which one is better and which one should I use in general ?

Yes.
Since function g doesn't have the argument name, the argument is not available for use within the function.

This type of declaration is commonly used to avoid compiler warnings or errors.
Example

int foo(int xyz)
{
  return 3;
}

Some compilers will give a warning for the above function.
*** Waring variable xyz declared but not used *****

To avoid such a warning, you could declare the function without the argument name.

int foo(int)
{
  return 3;
}

Now the compiler will not give a warning for unused variable.

Of course, if you don't need the variable, then you shouldn't have it in the function declaration.
However, this method is usefull when a function argument is no longer needed but you dont' wish to change all the code that is calling the function.
0
 
LVL 10

Assisted Solution

by:Sys_Prog
Sys_Prog earned 80 total points
ID: 9741117
Just to add, the above technique is termed as having Place-Holder Arguments

It is used when u know want to keep some dummy parameter to a function, so that u could use it later without affecting the client code using that function

HTH

Amit

0

Featured Post

Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article shows you how to optimize memory allocations in C++ using placement new. Applicable especially to usecases dealing with creation of large number of objects. A brief on problem: Lets take example problem for simplicity: - I have a G…
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
The goal of the video will be to teach the user the concept of local variables and scope. An example of a locally defined variable will be given as well as an explanation of what scope is in C++. The local variable and concept of scope will be relat…
The viewer will learn how to use the return statement in functions in C++. The video will also teach the user how to pass data to a function and have the function return data back for further processing.

772 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question