substr
Returns the portion of string specified by the offset and length parameters.
Parameters
- string
-
The input string.
- offset
-
If offset is non-negative, the returned string will start at the offset'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 offset is negative, the returned string will start at the offset'th character from the end of string.
If string is less than offset characters long, an empty string will be returned.
Using a negative offset<?php
$rest = substr("abcdef", -1); // returns "f"
$rest = substr("abcdef", -2); // returns "ef"
$rest = substr("abcdef", -3, 1); // returns "d"
?> - length
-
If length is given and is positive, the string returned will contain at most length characters beginning from offset (depending on the length of string).
If length is given and is negative, then that many characters will be omitted from the end of string (after the start position has been calculated when a offset is negative). If offset denotes the position of this truncation or beyond, an empty string will be returned.
If length is given and is 0, an empty string will be returned.
If length is omitted or null, the substring starting from offset until the end of the string will be returned.
Using a negative length<?php
$rest = substr("abcdef", 0, -1); // returns "abcde"
$rest = substr("abcdef", 2, -1); // returns "cde"
$rest = substr("abcdef", 4, -4); // returns ""; prior to PHP 8.0.0, false was returned
$rest = substr("abcdef", -3, -1); // returns "de"
?>
Return Values
Returns the extracted part of string, or an empty string.
Changelog
| Version | Description |
| 8.0.0 | length is nullable now. When length is explicitly set to null, the function returns a substring finishing at the end of the string, when it previously returned an empty string. |
| 8.0.0 | The function returns an empty string where it previously returned false. |