function overloading vs default argument in c++

Question

Hi i have a confusion or to say more i need to understand something. I have a procedure and another overloaded procedure of same.

    string conct (string a, string b) {
      string str = conct(a, b, "string");
      return str;
    }

    string conct (string a, string b, const char* c) {
      // do the processing;
      return concatenated_string;
    }

is it possible that instead of having two overloaded functions, if i make c in the overloaded function as default argument. So that even if someone passes only two arguments, i can just have one function to handle that case.

But my main concern comes in the third argument which is currently const char* c. So if i make it to something like const char* c = "string", would it be correct way to handle the case of removing overloading with one function with default argument.

I saw the post here but that seems to be focused on compilation and not the confusion i have.

I also have a small question, function overloading helps improving maintainability. But does it affect the overall performance when the overloaded procedures are invoked very frequently. — Puneet Mittal
– Puneet Mittal, Commented Jan 11, 2013 at 19:12
Regarding your comment: function overloading is resolved at compile time, so it has absolutely no effect on runtime performance. — Angew is no longer proud of SO
– Angew is no longer proud of SO, Commented Jan 11, 2013 at 19:17

bames53 · Accepted Answer · 2013-10-17 15:52:37Z

4

Yes, you can replace your overloaded functions with one function and a default argument:

string conct (string a, string b, const char* c = "string") {
  // do the processing;
  return concatenated_string;
}

When you overload functions the compiler generates code for each function, probably resulting in larger code size.
If an overload just acts as a thin wrapper as in your case then the optimizer may eliminate the extra work.
default arguments get set at the caller's location, rather than inside the function, so default arguments must be publicly visible, and changing them requires recompiling all callers. With an overload like yours the psuedo-default argument becomes a hidden detail.

edited Oct 17, 2013 at 15:52

answered Jan 11, 2013 at 19:24

bames53

88.7k15 gold badges191 silver badges255 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Puneet Mittal Over a year ago

So generally speaking, whether i remove the first function and add the third arg as default in second, or not, it doesn't really helps in any performance in my case.

theAlias Over a year ago

upvote for adding "default arguments get set at the caller's location, rather than inside the function". That explains why we need not specify default value in definition of the method

Arunima Saxena · Accepted Answer · 2015-06-05 12:13:20Z

0

default values can be used in function prototypes but if we want to default middle argument then we'll have to default all values to its right... On the other hand overloading a function can be done for all possible argument combinations also default value needs not to be placed on function call stack and thus less work for the compiler...

answered Jun 5, 2015 at 12:13

Arunima Saxena

1

Collectives™ on Stack Overflow

function overloading vs default argument in c++

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related