Differences between explode and split in php

We encountered some problems when using split today. I still do not have a deep understanding of the function. I will make a mark in the close-up. First, let's look at the definitions of the two methods:

Function prototype: array split (string $ pattern, string $ string [, int $ limit])

Function prototype: array explode (string $ separator, string $ string [, int $ limit])

There is no difference at first glance, and it seems that all functions are the same. I made this mistake. Note that the first parameters of the two functions are string $ pattern and string separator. $ pattern indicates a regular string, and $ separator indicates a normal string.

See the following code:
The code is as follows:
$ Test = end (explode ('.', 'abc.txt '));
Echo $ test; // output txt

Replace:
The code is as follows:
$ Test1 = end(split('.', 'abc.txt '));
Echo $ test1; // no output

The correct method to use split is to add escape characters.
The code is as follows:
$ Test1 = end (split ('\ .', 'abc.txt '));
Echo $ test1; // output txt


Analysis: The "." symbol is the keyword of the regular expression, so split is invalid, while explode is valid.