Conditions and use of if, elseif or ORed ifs

[mickey]

I want to know which of the following is better and why. Can you please let me know your thoughts? - Thanks

Set one
----------

if (varialbe == something)
{
//identical code
}

if (variable == somethingElse)
{

//identical code
}


Set two
----------

if (varialbe == something)
{
//identical code
}
elseif (varialbe == somethingElse)
{
//identical code
}
endif


Set 3
-------
if (varialbe == something || variable == somethingElse)
{
//identical code
}


// identical code - excatly same line of code in both the conditions

[CornedBee]

The third is the best of course.
The first duplicates the code and does the unnecessary second check even if the first succeeded.
The second doesn't do the check, but still duplicates the code.
The third has neither shortcoming.

[mickey]

This is what I too know. I was reviewing some code and I need to give actual reasons so as to why third is better over other two.

1) code size less
2) more readable
3) more efficient

Can you let me know others? like time exectuion, binary etc .

Thanks

[treuss]

Originally posted by mickey
why third is better over other two.

Maintainability!

Imagine you want to change the code that is done in the
//identical code
section. At how many places do you want to change it?

[TheCPUWizard]

Of course (due to what may be a type) the code in the first example may actually run twice, where this can not happen in the secondand third.

If that is a typo, then option 3 will typically b the best bet. Remember to put the most likely (if there is one) condition first to get maximum benefit from short circuiting.

[Mick]

It is going to be optimize anyway...so why not make it readable...2 or 3 are fine though I'd go with the 3...

[ferox]

Third one is offcourse the best way to go if you have the same code for both the conditions otherwise choose second one. (no endif in C++).