memory exhausted on line 2860 with (if else) - php

Question

I've searched in various places for this solution, but have not been able to solve the problem that happened to me. What happens is actually in the following code:
[21-Jul-2017 23:35:30 UTC] PHP Parse error: memory exhausted in
/home/.../public_html/folder/index.php on line 2860
Chronologically, I want to create many options if one of the options is met. Here's the problem code:
<?php
if(isset($_GET['url'])) {
$u = $_GET['url'];
if($u == 'old/page1.html') {
header('Location: /new/page1.htm');
} if($u == 'old/page2.html') {
header('Location: /new/page2.htm');
} if($u == 'old/page3.html') {
header('Location: /new/page3.htm');
} if($u == 'old/page4.html') {
header('Location: /new/page4.htm');
}
//.....
//.....(line 5691)
}
?>
If I only use the above code, then it can run normally. But if I use my code number of 5691 lines, then the warning starts to appear and the site can not be opened.
I suspect there is a problem on the maximum amount of memory used, but do not know exactly.

Answer 1

If you really need to sort it out this way, then this would probably be better:
<?php
if (isset($_GET['url'])) {
$u = $_GET['url'];
$redirects = [
'old/page1.html' => '/new/page1.htm',
// ...
];
if (array_key_exists($u, $redirects)) {
$redirect = $redirects[$u];
header(sprintf(
'Location: %s',
$redirect
));
}
}
This way at least you can manage the redirect mapping separately, without the need to add a bunch of conditions.
You could also put the mapping into a separate file:
<?php
return [
'old/page1.html' => '/new/page1.htm',
// ...
];
and then adjust your script:
<?php
if (isset($_GET['url'])) {
$u = $_GET['url'];
$redirects = require __DIR__ . '/redirects.php';
if (array_key_exists($u, $redirects)) {
$redirect = $redirects[$u];
header(sprintf(
'Location: %s',
$redirect
));
}
}
This way you don't need to modify your script if the mapping changes.
Alternatively, use elseif:
<?php
if (isset($_GET['url'])) {
$u = $_GET['url'];
if ($u == 'old/page1.html') {
header('Location: /new/page1.htm');
} elseif ($u == 'old/page2.html') {
header('Location: /new/page2.htm');
} elseif ($u == 'old/page3.html') {
header('Location: /new/page3.htm');
} elseif ($u == 'old/page4.html') {
header('Location: /new/page4.htm');
}
}

Answer 2

You can replace those 5691 lines of code with this
if(isset($_GET['url'])) {
$u = $_GET['url'];
if(substr($u, 3) === 'old'){
$new = str_replace('old', 'new', $u);
header("Location: $new");
}