I have an array with 3 entries like that:
0 => "Banana",
1 => "Apple",
2 => "Strawberry"
Now, when using a for-loop like:
for($i = 1; $i < $foo; $i++) {
$myarray[$i] = $fruitarray[$i];
}
And $i gets higher than 2, we run out of this $fruitarray. So what I want to do now is always to start at the beginning of the array when it's over. So that 3 outputs "Banana", 7 "Apple" etc.
What is the best practice to achieve this (especially if $fruitarray contains many entries)?
This is generally accomplished using the modulo operator.
for($i = 1; $i < $foo; $i++) {
$myarray[$i] = $fruitarray[$i % count($fruitarray)];
}
$i >= $foo? -- You could just fix that by removing the for loop condition.
for($i = 1; $i < $foo; $i++) {
$myarray[$i] = $fruitarray[$i%3];
}
Notice the $i%3, this is pronounced "i mod 3" and it means divide i by 3, and return the leftovers. So, 4%3=1, 7%3=1, 11%3=2, etc.
Just make sure $foo is more than 3, and this should wrap around. If $fruitarray is arbitrarily bigger than 3 items, use
$i%count($fruitarray)
One possible solution would be to check for when $i is equal to $foo - 1 and reset it to 1:
for($i = 1; $i < $foo; $i++) {
$myarray[$i] = $fruitarray[$i];
if($i == ($foo - 1))
$i = 1;
}
$foo > count($fruitarray) which is almost certainly the case.You should to use the modulus operator (Modulus remainder of $a divided by $b)
for($i = 1; $i < $foo; $i++) {
$j=$i%count($fruitarray);
$myarray[$i] = $fruitarray[$j];
}
Doing this with eager code is essentially intractable, as it would cause an infinite loop:
$i = 0;
$numFruits = count($fruitarray);
while (true) { // infinite loop!
$myarray[$++i] = $fruitarray[$i % $numFruits];
}
But you can come up with working code if, instead of an array, you use a function to fetch the value:
function getFruitAt($index) use ($fruitarray) {
$numFruits = count($fruitarray);
$realIndex = $index % $numFruits;
return $fruitarray[$realIndex];
}
Or, if you want to get fancy, you can use a generator or define your own Iterator type.
