I trying to print simple numbers from 1 to 10 using a for loop like this:
for($i = 0; $i <= 10; $i++){
if($i != 4 || $i != 6){
echo $i."<br/>";
}
}
Output:
0
1
2
3
4
5
6
7
8
9
10
I just want the output from 0 to 10 but the output should not contain the numbers 4 and 6.
It is working fine if I use the && operator but does not work if I use||.
I do not understand why this is not working - I think it should work with ||.
You don't want to print either 4 or 6, so you should be using &&.
The statement if($i != 4 || $i != 6) will trigger whenever $i is not equal to 4, or whenever $i is not equal to 6. Considering 4 is not equal to 6, it will trigger in both cases. It will reach $i = 4, and realise that $i is not equal to 6. This will step into the condition, as you say it only has to hold true for one or the other.
The statement if($i != 4 && $i != 6) implies that $i is not equal to 4 and $i is not equal to 6. Both conditions must hold true at the same time. When $i = 4, $i != 6 will be true, but $i != 4 will be false. Both conditions need to be true, so it will fail. Essentially, this could be rewritten as:
for($i = 0; $i <= 10; $i++){
if($i != 4) {
if($i != 6) {
echo $i."<br/>";
}
}
}
To skip over the numbers 4 and 6 in the loop, you have to use the and condition:
for($i = 0; $i <= 10; $i++){
if($i != 4 && $i != 6){
echo $i."<br/>";
}
}
Hope this helps!
You want &&. It would not work with ||; that means something different.
"x && y" means "only true if x is true and y is also true; otherwise false."
"x || y" means "true if either x is true or y is true; only false if both are false."
The contrapositive (i.e., "opposite") of ($i != 4 && $i != 6) is ($i == 4 || $i == 6).
Mixing in the || without swapping the comparisons as well means, in your case, "true if $i is not 4, or also true if $i is not 6." Since one of those cases must always true, the result is also always true.
<?php for ($i=0; $i < 10 ; $i++) {
if ($i != 4 && $i !=6){
echo $i."<br>";}}
?>
$i != 4 || $i != 6is always true. It could only be false for aniwhich is both4and6at the same time...&&