Remove the first few lines from a string in PHP

Problem: I have a multiline string - not a file - and I want to remove the first few lines from it and keep the rest. I found this surprisingly unintuitive. So these are notes in case I want to do it again. Feel free to suggest a better way!

Example

Given this input:

 PHP$str = "Once upon\nA Time\nLived a big\nDragon\nCalled Cuthbert.";

I want the output to be:

 PHP"Dragon\nCalled Cuthbert."

That is, remove the first X lines in a string.

Exploding kittens

Using explode() converts a string into an array based on a delimiter character.

If limit is set and positive, the returned array will contain a maximum of limit elements with the last element containing the rest of string.

This code removes the first three lines and keeps the rest

 PHP$str = explode("\n", $str, 4)[3];

Here's a way to visualise what's going on:

 PHP$str = "1\n2\n3\n4\n5\n6";

print_r(explode("\n", $str, 4));

Outputs:

 PHPArray

(

    [0] => 1

    [1] => 2

    [2] => 3

    [3] => 4\n5\n6

)

What not to do...

• Loop through the string, counting the instances of \n and then substringing based on that position.
• Write the string to a file and then read it line by line.