How to print odd/even series without if-statement - php

Question

I'm writing program to list odd/even series from n elements (1,2,...n) using if-statement.
For example,
n = 1
Odd Series
1
3
5
7
9
Even Series
0
2
4
6
8
If any possible to print odd/even series without if-statement.

Answer 1

You can just use range with a step of 2, starting with either 0 or 1 as required:
echo "Odd Series\n";
foreach (range(1, 9, 2) as $v) echo "$v ";
echo "Even Series\n";
foreach (range(0, 9, 2) as $v) echo "$v ";
Output:
Odd Series
1 3 5 7 9
Even Series
0 2 4 6 8
Demo on 3v4l.org

Answer 2

Yes. This is possible. We can list odd or even series without if-condition.
We use Increment operator insteed of if-condition.
Sample code is,
<?php
echo "Odd Series";
echo "<pre>";
for ($i=0; $i < 10; $i++) {
echo ++$i;
}
echo "Even Series";
echo "<pre>";
for ($i=0; $i < 10; $i++) {
echo $i++;
}
?>
Sample output is here,
Odd Series
1
3
5
7
9
Even Series
0
2
4
6
8

Answer 3

We could try using a ternary expression in lieu of an if statement:
// even series
for ($i = 0; $i < 10; $i++) {
echo $i % 2 == 0 ? $i : "\n";
}
Another possibility is to just iterate the for loop by steps of 2:
for ($i = 0; $i < 10; $i=$i+2) {
echo $i . "\n";
}

Answer 4

Using arrays, you can create the range with range(), and use array_filter() to pluck the odd or even values using bit-operators.
$n = 8;
$series = range(1, $n);
$odd = array_filter($series, function($value) { return $value & 1; });
$even = array_filter($series, function($value) { return !($value & 1); });
var_dump($odd, $even);
Then its just a matter of looping the arrays $odd and $even.
echo "Odd values: \n";
foreach ($odd as $v) {
echo $v."\n";
}
echo "Even values: \n";
foreach ($even as $v) {
echo $v."\n";
}
Live demo at https://3v4l.org/J9Dio