What should be the approach to avoid duplicate code in below pseudo c code snippet?

Question

if(var == something) {
    A();
    B();
} else if(var == something_else) {
    A();
    B();
    C();
} else {
    assert(false);
}

How can i avoid duplicate code of calling A() and B() in both if cases. Should i use switch case like,

switch(var) {
case something:
case something_else:
    A();
    B();
    break;
}
if (var == something_else)
   C():

What is the better solution? Is there any performance penalty in switch vs if else?

Example you've given is extremely simple, and it seems that trying to minimize code reuse in this case is not worth the effort. It only makes code harder to read. — user694733, Oct 20 '15 at 10:19
@user694733, This is just example for what i am trying to do in complex framework. — Jagdish, Oct 20 '15 at 10:26

score 6 · Answer 1 · edited May 23 '17 at 12:14

if (var == something || var == something_else) {
    A();
    B();
}

if (var == something_else) {
    C();
}

If you also need the else, you can do this:

if (var == something || var == something_else) {
    A();
    B();

    if (var == something_else) {
        C();
    }
} else {
    assert(false);
}

In regards to your question,

Is there any performance penalty in switch vs if else?

Please read the answers to this question:

Is 'switch' faster than 'if'?

In short, normally there wouldn't be any noticeable difference. So you should write your code with the readability in mind. Between if/else and switch, just choose whatever is more natural.

score 2 · Accepted Answer · answered Oct 20 '15 at 09:56

2

As calling order doesn't matter, try this:

switch(var) {    
    case something_else:
        C();
    case something:
        A();
        B();
    break;
    default:
        assert(false);
    break;
}

answered Oct 20 '15 at 09:56

mazhar islam

5,561
3
20
41

score 2 · Answer 3 · edited Oct 20 '15 at 10:04

2

You can use a nested if statement for this, like so:

If (var == something || var == something_ese) {
    A();
    B();
    If (var == something_else) { C(); }
}
Else
{
    Assert(false);
}

edited Oct 20 '15 at 10:04

Sufian Latif

13,086
3
33
70

answered Oct 20 '15 at 09:57

Magisch

7,312
9
36
52

score 1 · Answer 4 · answered Oct 20 '15 at 10:11

I would suggest separating the assert and the work:

assert(var == something || var == something_else);

A();
B();
if(var == something_else) {
    C();
}

Not only this avoids duplication of A and B calls, but also makes it more readable as you specify the pre-requisites right at the beginning.

What should be the approach to avoid duplicate code in below pseudo c code snippet?

4 Answers4