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substr

Returns the portion of string specified by the start and length parameters. Test substr online.

string substr ( string $string , int $start [, int $length ] )

PHP Documentation by the PHP Documentation Group

substr

(PHP 4, PHP 5, PHP 7, PHP 8)

substrReturn part of a string

Description

substr ( string $string , int $offset , int|null $length = null ) : string

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, false will be returned.

Example #1 Using a negative offset

<?php
$rest 
substr("abcdef", -1);    // returns "f"
$rest substr("abcdef", -2);    // returns "ef"
$rest substr("abcdef", -31); // 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, false will be returned.

If length is given and is 0, false or null, an empty string will be returned.

If length is omitted, the substring starting from offset 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.

Errors/Exceptions

Returns false on error.

<?php
var_dump
(substr('a'2)); // bool(false)
?>

Changelog

Version Description
8.0.0 length is nullable now.
8.0.0 The function returns an empty string where it previously returned false.

Examples

Example #3 Basic substr() usage

<?php
echo substr('abcdef'1);     // bcdef
echo substr('abcdef'13);  // bcd
echo substr('abcdef'04);  // abcd
echo substr('abcdef'08);  // abcdef
echo substr('abcdef', -11); // 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"02), true).PHP_EOL;
echo 
"2) ".var_export(substr(5432102), true).PHP_EOL;
echo 
"3) ".var_export(substr(new apple(), 02), true).PHP_EOL;
echo 
"4) ".var_export(substr(true01), true).PHP_EOL;
echo 
"5) ".var_export(substr(false01), true).PHP_EOL;
echo 
"6) ".var_export(substr(""01), true).PHP_EOL;
echo 
"7) ".var_export(substr(1.2e304), true).PHP_EOL;
?>

The above example will output:

1) 'pe'
2) '54'
3) 'gr'
4) '1'
5) ''
6) ''
7) '1200'

See Also

PHP Documentation

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