Substring to take all letters after the 4th character

Question

I only have a basic understanding of substring. I am trying to extract the first 4 characters as a string variable and extract the rest of the characters in another string variable. How may I do this with substring? With PHP

$rest = substr("jKsuSportTopics", -3, 1);
$rest2 = substr("jKsuSportTopics", 4, 0);

Answer 1

The second argument is the starting index, and the third argument is the length of the string. If the 3rd argument is missing, you'll get the rest of the string.

$first_part = substr("jKsuSportTopics", 0, 4);
$rest = substr("jKsuSportTopics", 4);

Here's a quote from the docs:

...the returned string will start at the start'th position in string, counting from zero. For instance, in the string 'abcdef', the character at position 0 is 'a', the character at position 2 is 'c', and so forth.

[...]

If length is given and is positive, the string returned will contain at most length characters beginning from start (depending on the length of string).

[...]

If length is omitted, the substring starting from start until the end of the string will be returned.