What if I want to make each case in the switch case been a equlity condition like this code example
switch (true){
case X==Y:
//do something
case X==Z:
//do something
case X has 0 :
//do something
}
Its working well if I want to check only one condition,By adding break
,But what if i want to check all cases and do only true cases
If you want to change flavor from if.....else and want to use switch....case
So you can try like this
$test = true;
$x=1;$y=1;$z=2;//uncomment any one and check
//$x=1;$y=2;$z=1;//uncomment any one and check
//$x=0;$y=1;$z=1;//uncomment any one and check
switch ($test){
case $x==$y:
echo "x==y";
break;
case $x==$z:
echo "x==z";
break;
case $x==0 :
echo "x has 0";
break;
default:
echo "he!he!he!he!he!he!";
}
uncomment any one and check all conditions
Check demo here : https://eval.in/907483
Here using $test = true; means if your condition goes true in case inside switch
Related
In pick basic there is a case command which functions similar to the switch command basically doing nested if then else commands. The code is like this:
begin case
case a=4;do something
case b=5 or c=6;do something
case y=x and f=z;do something
case 1;do something
end case
if any of the conditions are true, it falls into that case. I know PHP has the switch command, but that is limited to the value of one variable. Is there a way to code the above in PHP or javascript for that matter without a bunch of if then else commands similar to the above?
If you really don't want to use if/else, then switch (true) can work:
switch (true) {
case ($a === 4):
doSomething();
break;
case ($b === 5 || $c === 6):
doSomething();
break;
case ($y === $x || $f === $z):
doSomething();
break;
default:
break;
}
However, it is less typing, and it makes your code more readable, if you simply use if/else instead, just as Shomz suggested. I really wouldn't recommend using switch (true).
Replacing case with else if is only 3 bytes longer, I don't see the big deal because that is exactly what the if/else is for. Switches are used for single variables, as you said.
Your do something could also include a result variable or a flag that will be set if any of the conditions are met.
So this:
begin case
case a=4;do something
case b=5 or c=6;do something
case y=x and f=z;do something
case 1;do something
end case
could be:
var case = false;
if (a==4) {dosomething(); case = true}
else if (b==5 || c==6) {dosomething(); case = true}
else if (y==z || f==z) {dosomething(); case = true}
else if (1) {dosomething(); case = true} // supposedly the default case?
I have the following if statement (except the final one would be much longer with more values) that I would like to condense.
if ($row['titleId'] == '123' || $row['titleId'] == '456' || $row[){
I would imagine it would end up something like:
if ($row['titleId'] == ('123'||'456'){}
Or would I be better off like this:
$array = ('123','456')
if (in_array($row['titleId'], $array){}
You can use switch for this:
switch ($row['titleId']) {
case '123': case '456': case '789': case '314': case '271':
doSomething();
}
I'd probably still prefer to have each case on a separate line but, if your goal is to reduce the "height" of your code, you can do it as above.
In terms of shortening the code in your comment, which apparently looks like this:
switch($row['titleId']){
case '8216': case '8678': case '8705': case '8216': case '8707':
$rows[$row['titleId']]=array();
break;
case '8214':
$rows['8216'][]=$row['titleId'];
break;
case '8791':
$rows['8678'][]=$row['titleId'];
break;
case '8643':
$rows['8705'][]=$row['titleId'];
break;
case '8666':
$rows['8707'][]=$row['titleId'];
break;
}
you could opt for something like:
$xlat = array('8214'=>'8216', '8791'=>'8678', '8643'=>'8705', '8666'=>'8707');
switch($row['titleId']){
case '8216': case '8678': case '8705': case '8216': case '8707':
$rows[$row['titleId']]=array(); break;
default:
if (array_key_exists($row['titleId'],$xlat)) {
$rows[$xlat[$row['titleId']]][]=$row['titleId'];
}
}
This compresses the common cases by putting them under the control of an associative array. Basically, if the title ID is in the array as a key, its lookup value will be used to affect the correct $rows entry.
I have a switch statement with 3 cases,like this:
switch($date) {
case 1:
echo "";
break;
case 2:
echo "";
break;
case 3:
echo'';
break;
default:
echo '';
break;
}
And i am wondering,if there is a way to loop through all cases if they are all true.But with using break,because if i am not using it,the cases wont work properly.So is there a way???
You shouldn't use switch if you want to see if multiple things are true about the variable in question since the switch statement will cut out once one of the cases holds true (i.e. it won't continue to look to see if the other cases also apply to the variable).
If your goal is to test if multiple things are true regarding a variable, just use an if statement:
if ($date == X && $date == Y && $date == Z) {
// Do something since all the conditions are met
}
Another possibility is to "fall through" your cases like this:
switch ($variable) {
case 0:
// Do something to (some) variable to indicate this case applies
case 1:
// Do something to (some) variable to indicate this case also applies
case 2:
// Do something to (some) variable to indicate this case also applies
echo "WHATEVER YOU WANT TO ECHO"
break;
}
Here is my code I wanted to ask if there is a better way to do this? I'm going to need more "else if" options and I'm worried about performance
if($_GET['begin'] === 'yeg'){
} else if ($_GET['begin'] === 'deda') {
} else if ($_GET['begin'] === 'beara') {
} else if ($_GET['begin'] === 'eima') {
} else if ($_GET['begin'] === 'aba') {
}
You should use switch statement instead. A switch construct is more easily translated into a jump (or branch) table. This can make switch statements much more efficient than if-else when the case labels are close together. The idea is to place a bunch of jump instructions sequentially in memory and then add the value to the program counter. This replaces a sequence of comparison instructions with an add operation. - #Judge Maygarden
Why the switch statement and not if-else?
$begin = $_GET['begin'];
switch ($begin):
case 'yeg':
//do something
break;
case 'deda':
//do something
break;
case 'beara':
//do something
break;
case 'eima':
//do something
break;
case 'aba':
//do something
break;
endswitch;
You can try to use a switch statement instead:
switch ($_GET['begin']) {
case 'yeg':
break;
case 'deda':
break;
// Yada yada, continue like this as much as needed.
}
I use javascript to send cases to and ajax function. The cases are taken from the link id. For example, if user clicked this link:
<a id="answer-yes-123">click this</a>
The javascript will split the id to 3 part, and send the middle part "yes" to ajax as a case. For most cases, when ajax receives the case, if yes do this if no do that.
switch ($case) {
case 'yes' :
$assignment->add();
break;
case 'no' :
$assignment->remove();
break;
There's one exception-- a numerical case. If the middle part of the link is a number, I don't know how to make the switching statement. There are potentially unlimited different numbers, I can't make each of them a case, How to make a condition like if(is_int($case)) to work as a case?
In the switch default: case, you can test is_int():
switch ($case) {
case 'yes' :
$assignment->add();
break;
case 'no' :
$assignment->remove();
break;
default:
// Determine the numeric value however you need to
// is_int(), is_numeric(), preg_match(), whatever...
if (is_int($case)) {
// numeric stuff
}
}
This is a little strange logically, because default: is typically used for the do this if nothing else is met condition. In your case though, if you don't need to further divide the numeric case much it works. Just be sure to comment it clearly in your code so you remember why you did it when you look back on it in six months.
Update after comments:
Since you already used the default:, I believe you can actually use an expression inside a case. This warrants even clearer commenting since it is not a common practice and goes kind of against the purpose of a switch:
switch ($case) {
case 'yes' :
$assignment->add();
break;
case 'no' :
$assignment->remove();
break;
// This actually works, but is highly weird.
// One of those things I can't believe PHP allows.
// is_int(), is_numeric(), preg_match(), whatever...
case is_int($case):
// Numeric stuff
break;
default:
// default stuff
}
Write the if-statement around the switch.
Something like this comes to my mind:
if (is_int($case)) {
// ...
} else {
switch ($case) {
// ...
}
}
Michael Berkowski's answer is perfect, but if don't want to use default case like this that could work also:
switch (preg_replace('/^[0-9]*$/','numeric',$case)) {
case 'yes' :
$assignment->add();
break;
case 'no' :
$assignment->remove();
break;
case 'numeric' :
$assignment->remove();
break;
default:
//...
break;
}
Use PHP's is_numeric
http://php.net/manual/en/function.is-numeric.php
if (is_numeric($case)) {
// ...
} else {
switch ($case) {
// ...
}
}