Put the value of for loop inside array - php

Question

I am trying to reate an array that contains all the odd numbers between 1 to 20,000. I Use the var_dump() at the end to display the array values without using loops.
For some reason it won't work out.
here's my code so far:
$array_variable = array();
for($i=1; $i<=20000; $i++){
if($i%2 == 1){ // if the remainder after division `$i` by 2 is one{
print_r($array_variable[$i]); // if odd, echo it out and then echo newline for better readability;
}
}
var_dump($array_variable);

Answer 1

You need to push the values to your array first:
$array_variable = array();
for($i=1; $i<=20000; $i++){
if($i%2 == 1){
$array_variable[] = $i;// or array_push($array_variable, $i);
}
}
var_dump($array_variable);
Otherwise your array stays empty.

Answer 2

This results in alot of undefined indexes because you're not adding anything to $array_variable.
Change the code to this:
$array_variable = array();
for($i=1; $i<=20000; $i++){
if($i%2 == 1){ // if the remainder after division `$i` by 2 is one{
$array_variable[] = $i; // $array_variable[] means adding something to the array
}
}
var_dump($array_variable); //dump all odd numbers
For better readability of the array you could use:
echo "<pre>";
print_r($array_variable);
echo "</pre>";

Answer 3

Your $array_variable is empty because you never add any elements to it. Try this instead:
$array_variable = range(1, 20000, 2);

Answer 4

$array_variable = array();
for($i=1; $i<=20000; $i++){
if($i%2 == 1){ // if the remainder after division `$i` by 2 is one{
array_push($array_variable, $i); //Push the variable into array
}
}
var_dump($array_variable); //dump all odd numbers

Answer 5

You are trying to print an element it does not exist since the array is empty.
If you insist on using an array use this code, you notice you assign a value to the array elements: ( and also if you want to display it on a new line in browser, use echo commented out): (if interested about more: what is the difference between echo and print_r
<?php
$array_variable = array();
for($i=1; $i<=20000; $i++){
$array_variable[$i]=$i;//assignment
if($i%2 == 1){ // if the remainder after division `$i` by 2 is one{
print_r($array_variable[$i]); // if odd, echo it out and then echo newline for better readability;
//echo $array_variable[$i].'<br>';
}
}
var_dump($array_variable);
?>