Is there any reason to use switch statement instead of strings of if and elseif?

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Advantage of switch over if-else statement
Why the switch statement and not if-else?

The switch statement seems to be totally useless. Anything it can do can be done by if and else if link.

They probably even compile to the same code.

So why bother having it?

The break statements in switch drives me crazy and that label: format reminds me of goto.

This is for objective-c, c, C++. I am not sure if vb.net has switch statement, but even if it does I must have forgotten because I never use it.

Same question as: http://stackoverflow.com/questions/449273/why-the-switch-statement-and-not-if-else ? — happy coder, Jan 02 '13 at 06:38
By your logic, `if` and `else` are useless because switch can accomplish the same work. :/. — Zéychin, Jan 02 '13 at 06:40
Why have if, switch, while, and for when you can just use goto? — djechlin, Jan 02 '13 at 06:40
while is for loop (actually it's useless because we have for) — user4234, Jan 02 '13 at 07:09
http://stackoverflow.com/questions/1028437/why-switch-case-and-not-if-else-if — qrdl, Jan 02 '13 at 08:57

score 10 · Accepted Answer · answered Jan 02 '13 at 06:37

10

They may well compile to the same code. But the intent is not necessarily to provide better compiled code so much as it is to provide better source code.

You can do while or for loops with if and goto as well but that doesn't make while and for useless. Would you rather have:

for (i = 0; i < 10; i++)
    doSomethingWith (i);

or:

    i = 0;
loop12:
    if (! (i < 10))
        goto skip12
    doSomethingWith (i);
    i++;
    goto loop12
skip12:

answered Jan 02 '13 at 06:37

paxdiablo

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+1 for "You can do while loops with if and goto as well but that doesn't make while useless." – Yavar Jan 02 '13 at 06:39

legends2k · Answer 2 · 2020-12-07T05:21:53.487

3

if (color == WHITE)
{
}
else if (color == BLACK)
{
}
else if (color == GREY)
{
}
else if ((color == ORANGE) || (color == GREEN) || (color == BLUE))
{
}
else
{
}

vs

switch(color)
{
   case WHITE:
       break;
   case BLACK:
       break;
   case GREY:
       break;
   case ORANGE:
   case GREEN:
   case BLUE:
       break;
   default:
       break;
}

Isn't the latter more readable and requires lesser key strokes?

Apart from readability there's another unique use of switch-case: Duff's Device. This technique exploits the goto-ness of switch-case coupled with while.

void dsend(char* to, char* from, count) {
  int n = (count + 7) / 8;
  switch (count % 8) {
  case 0: do {
      *to = *from++;
      case 7: *to = *from++;
      case 6: *to = *from++;
      case 5: *to = *from++;
      case 4: *to = *from++;
      case 3: *to = *from++;
      case 2: *to = *from++;
      case 1: *to = *from++;
    } while (--n > 0);
  }
}

edited Dec 07 '20 at 05:21

answered Jan 02 '13 at 06:41

legends2k

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no the former is more readable and gives developer more freedom to make changes later for specific cases – Mahammad Isgandarli Mar 28 '20 at 09:36
I agree that readability is subjective, but I don't understand the freedom part. Can you please explain how `if` gives more freedom over `switch-case`? – legends2k Dec 07 '20 at 05:25
If you wanted to change the logic in `else if ((color == ORANGE) || (color == GREEN) || (color == BLUE))` for example, it would be easier using the else if. – whackamadoodle3000 Feb 09 '21 at 04:06

score 1 · Answer 3 · edited May 23 '17 at 12:18

1

Performance of switch is same as if and else if blocks in the worst case. It may be better. This has been discussed before: Advantage of switch over if-else statement

edited May 23 '17 at 12:18

Community

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1

answered Jan 02 '13 at 06:39

russoue

5,180
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score 0 · Answer 4 · answered Jan 02 '13 at 06:41

0

Pros:

Switch offers a better way to write program than if

Switch works faster than if because during execution compiler generates jump table to decide which case is satisfied rather than checking which case is satisfied!

Cons:

case can only have int or char constants or an expression that evaluates to one of these!

answered Jan 02 '13 at 06:41

Anirudha

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Are you sure this isn't optimized into a jump table anyway? – djechlin Jan 02 '13 at 06:42
@djechlin it is indeed optimized in every language with jump table... – Anirudha Jan 02 '13 at 06:45
1

and if using if else it's not optimized? – user4234 Jan 02 '13 at 07:08

Is there any reason to use switch statement instead of strings of if and elseif?

4 Answers4