What is difference between Switch() and If statement ?

[shanali4]

In the following code I've used if statement

<?php
$country="";
if ($country=="Pakistan")
echo "Hi, You have selected Pakistan";
elseif ($country=="India")
echo "Hi, You have selected India";
elseif ($country=="United states")
echo "Hi you have selected US";
else
echo "Your country is not in our list";
?>

 

Now in the following code i've used PHP switch () function to accomplish the same task as by if statement

 

<?php
$country="";
switch ($country)
{
case "Pakistan";
echo "Hi, You have selected Pakistan";
break;
case "India":
echo "Hi, You have selected India";
break;
case "United states":
echo "Hi you have selected US";
break;
default:
echo "Your country is not in our list";
}
?>

 

If we add Pakistan, India or united state in $country variables in both of the codes and execute them the result would be same in case of both if statement and switch ().

 

So actually what is difference between switch() and if statement.

 

Waiting 4 reply.

 

[Daniel0]

So actually what is difference between switch() and if statement.

 

An if statement checks for a boolean, a switch statement checks one value against a number of other values.

[ignace]

It's for example harder to accomplish the below with a switch statement:

 

$value != 50

$value < 50

[Alex]

It's for example harder to accomplish the below with a switch statement:

 

$value != 50

$value < 50

It is possible though, with some atypical syntax.

 

switch(true)
{
    case $value != 50:
        // ...
        break;
}

[Daniel0]

$value != 50

 

switch ($value) {
    case 50:
        break;
    default:
        echo 'it is not 50';
}

 

$value < 50

 

$php = 'switch (floor($value)) {';
for ($i = 49; $i > ~PHP_INT_MAX; --$i) {
    $php .= "\n\tcase {$i}:";
}
$php .= "\n\t\techo 'it is less than 50';\n}";
eval($php);

 

Or like this, but that's cheating seeing as you're not using $value on the switch:

 

switch (true) {
    case ($value < 50):
        echo 'it is less than 50';
}

[ignace]

I said it's harder not impossible. We know this, the OP doesn't.

[Daniel0]

I didn't say you said it was impossible

[ignace]

It was actually in response to Alex who said: "It's possible though"

[Alex]

I never thought you meant it was impossible either. I was just stating that for the purposes of the OP who might not have known that.

[ignace]

$php = 'switch ($value) {';
for ($i = 49; $i > ~PHP_INT_MAX; --$i) {
    $php .= "\n\tcase {$i}:";
}
$php .= "\n\t\techo 'it is less than 50';\n}";
eval($php);

 

LOL, what if I were to check multiple numbers? How fast does that execute actually?

[Daniel0]

Dunno. I didn't execute it. I'm running on a 34-bit system, so ~PHP_INT_MAX == -9223372036854775808. It would take a lot of memory just generating the code.

[Mchl]

I'm running on a 34-bit system,

 

That's leet! Does it use heptadecimal insread of hexadecimal?

[BizLab]

To the original question :

 

In the following code I've used if statement

<?php
$country="";
if ($country=="Pakistan")
echo "Hi, You have selected Pakistan";
elseif ($country=="India")
echo "Hi, You have selected India";
elseif ($country=="United states")
echo "Hi you have selected US";
else
echo "Your country is not in our list";
?>

 

Now in the following code i've used PHP switch () function to accomplish the same task as by if statement

 

<?php
$country="";
switch ($country)
{
case "Pakistan";
echo "Hi, You have selected Pakistan";
break;
case "India":
echo "Hi, You have selected India";
break;
case "United states":
echo "Hi you have selected US";
break;
default:
echo "Your country is not in our list";
}
?>

 

If we add Pakistan, India or united state in $country variables in both of the codes and execute them the result would be same in case of both if statement and switch ().

 

So actually what is difference between switch() and if statement.

 

Waiting 4 reply.

 

 

The biggest difference you will see on this scale is how easily the conditional can be read. I would absolutely use the switch statement for your country selection box (its slightly faster on large scale switches, but this is insignificant here).

 

So, the bottom line: use switch because it is easier to understand while reviewing

 

PS DON'T FORGET TO ADD THE LAST BREAK TO YOUR DEFAULT CONDITION

[kenrbnsn]

You don't need to put a "break" statement in the last condition, since it is the last condition. The reason you have a "break" statement in the other conditions is to prevent PHP from executing any other statements after the one that matches. The "break" statement is not required in each condition. You can have something like:

<?php
switch ($value) {
    case 'a':
         $a = "do something for a";
    case 'b':
         $b = "do something for b";
         $both = "do something for both a & b";
         break;
    default:
         $n = "neither a or b";
}
?>

 

Ken

[ignace]

<?php
switch ($value) {
    case 'a':
         $a = "do something for a";
    case 'b':
         $b = "do something for b";
         $both = "do something for both a & b";
         break;
    default:
         $n = "neither a or b";
}
?>

 

It may be not so clear as to what Ken was trying to explain but when you pass the value a, both a and b will execute. Not default as a break has been added before default: When you pass the value b only b is executed.

 

What I'm trying to say is that, if you don't write the break it will fall-through (and execute all code in between) until a break is reached or the switch has ended.

[Daniel0]

I'm running on a 34-bit system,

 

That's leet! Does it use heptadecimal insread of hexadecimal?

 

Heh yeah, that was supposed to have been 64

[BizLab]

You don't need to put a "break" statement in the last condition, since it is the last condition. The reason you have a "break" statement in the other conditions is to prevent PHP from executing any other statements after the one that matches. The "break" statement is not required in each condition. You can have something like:

<?php
switch ($value) {
    case 'a':
         $a = "do something for a";
    case 'b':
         $b = "do something for b";
         $both = "do something for both a & b";
         break;
    default:
         $n = "neither a or b";
}
?>

 

Ken

 

I like to keep the code clean and consistent. To the original post, you will want to write switches with breaks after every condition you are comparing. Otherwitse the IF() conditional is more well suited.. it's good form to add the lastbreak, whether needed (technically) or not. THANKS