substr
substr
(PHP 4, PHP 5, PHP 7)
substr — Return part of a string
Description
string substr ( string $string , int $start [, int $length ] )
Returns the portion of string
specified by the start
and length
parameters.
Parameters
-
string
-
The input string. Must be one character or longer.
-
start
-
If
start
is non-negative, the returned string will start at thestart
'th position instring
, 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
start
is negative, the returned string will start at thestart
'th character from the end ofstring
.If
string
is less thanstart
characters long,FALSE
will be returned.Example #1 Using a negative
start
<?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 mostlength
characters beginning fromstart
(depending on the length ofstring
).If
length
is given and is negative, then that many characters will be omitted from the end ofstring
(after the start position has been calculated when astart
is negative). Ifstart
denotes the position of this truncation or beyond,FALSE
will be returned.If
length
is given and is 0,FALSE
orNULL
, an empty string will be returned.If
length
is omitted, the substring starting fromstart
until the end of the string will be returned.Example #2 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 false $rest = substr("abcdef", -3, -1); // returns "de" ?>
Return Values
Returns the extracted part of string
; or FALSE
on failure, or an empty string.
Changelog
Version | Description |
---|---|
7.0.0 | If string is equal to start characters long, an empty string will be returned. Prior to this version, FALSE was returned in this case. |
5.2.2 - 5.2.6 | If the start parameter indicates the position of a negative truncation or beyond, false is returned. Other versions get the string from start. |
Examples
Example #3 Basic substr() usage
<?php echo substr('abcdef', 1); // bcdef echo substr('abcdef', 1, 3); // bcd echo substr('abcdef', 0, 4); // abcd echo substr('abcdef', 0, 8); // abcdef echo substr('abcdef', -1, 1); // f // Accessing single characters in a string // can also be achieved using "square brackets" $string = 'abcdef'; echo $string[0]; // a echo $string[3]; // d echo $string[strlen($string)-1]; // f ?>
Example #4 substr() casting behaviour
<?php class apple { public function __toString() { return "green"; } } echo "1) ".var_export(substr("pear", 0, 2), true).PHP_EOL; echo "2) ".var_export(substr(54321, 0, 2), true).PHP_EOL; echo "3) ".var_export(substr(new apple(), 0, 2), true).PHP_EOL; echo "4) ".var_export(substr(true, 0, 1), true).PHP_EOL; echo "5) ".var_export(substr(false, 0, 1), true).PHP_EOL; echo "6) ".var_export(substr("", 0, 1), true).PHP_EOL; echo "7) ".var_export(substr(1.2e3, 0, 4), true).PHP_EOL; ?>
Output of the above example in PHP 7:
1) 'pe' 2) '54' 3) 'gr' 4) '1' 5) '' 6) '' 7) '1200'
Output of the above example in PHP 5:
1) 'pe' 2) '54' 3) 'gr' 4) '1' 5) false 6) false 7) '1200'
Errors/Exceptions
Returns FALSE
on error.
<?php var_dump(substr('a', 2)); // bool(false) ?>
See Also
- strrchr() - Find the last occurrence of a character in a string
- substr_replace() - Replace text within a portion of a string
- preg_match() - Perform a regular expression match
- trim() - Strip whitespace (or other characters) from the beginning and end of a string
- mb_substr() - Get part of string
- wordwrap() - Wraps a string to a given number of characters
- String access and modification by character
© 1997–2017 The PHP Documentation Group
Licensed under the Creative Commons Attribution License v3.0 or later.
https://secure.php.net/manual/en/function.substr.php