What is the difference between Switch and IF??

Question

I know this may be simple question but want to know every ones opinion on this.

what is the difference between switch and IF function in PHP?? What I can see is where ever "switch" function uses "IF" function also applies there..correct me if I am wrong..

Or any performance wise difference between two??

Answer 1

Or any performance wise difference between two??

Forget about the performance difference on this level- there may be a microscopic one, but you'll feel it only when doing hundreds of thousands of operations, if at all. switch is a construct for better code readability and maintainability:

switch ($value) 
 {
 case 1:   .... break;
 case 2:   .... break;
 case 3:   .... break;
 case 4:   .... break;
 case 5:   .... break;
 default:  .... break;
 }

is mostly much more clean and readable than

if ($value == 1) { .... }
elseif ($value == 2) { .... }
elseif ($value == 3) { .... }
elseif ($value == 4) { .... }
elseif ($value == 5) { .... }
else { .... }

Edit: Inspired by Kuchen's comment, for completeness' sake some benchmarks (results will vary, it's a live one). Keep in mind that these are tests that run 1,000 times. The difference for a couple of if's is totally negligeable.

• if and elseif (using ==) 174 µs
• if, elseif and else (using ==) 223 µs
• if, elseif and else (using ===) 130 µs
• switch / case 183 µs
• switch / case / default 215 µs

Conclusion (from phpbench.com):

Using a switch/case or if/elseif is almost the same. Note that the test is unsing === (is exactly equal to) and is slightly faster then using == (is equal to).

Answer 2

If you have simple conditions, like if something equates to something else, then a switch is ideal.

For example, instead of doing the following:

if($bla == 1) {

} elseif($bla == 2) {

} elseif($bla == 3) {

} etc...

It's better to do it like this:

switch($bla) {
  case 1:
    ...
    break;
  case 2:
    ...
    break;
  case 3:
    ...
    break;
  default:
    ...
    break;
}

Alternatively, if you have complex conditions, you should use an if/else.

I think that this is all a matter of opinion though - some people just don't use switch statements at all, and stick with if/else.

Answer 3

Don't forget, though, that a switch does not necessarily work as a simple if statement. Remembering that a switch does not require a break at the end of each case and leaving that break off allows you to 'fall through' to the next case, too, can allow some interesting and somewhat complex 'ifs'.

Answer 4

No, you are right.
There are not much difference between these statements.
You may use one you like.

Just bear in mind that if you have to use more than 3-4 consecutive conditions - that means you most likely have design faults.

Usually you can substitute such a statement with a loop or with more clear application design.