substr
(PHP 4, PHP 5, PHP 7)
substr — Return part of a string
Description
$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
startis 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
startis negative, the returned string will start at thestart'th character from the end ofstring.If
stringis less thanstartcharacters long,FALSEwill 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
lengthis given and is positive, the string returned will contain at mostlengthcharacters beginning fromstart(depending on the length ofstring).If
lengthis given and is negative, then that many characters will be omitted from the end ofstring(after the start position has been calculated when astartis negative). Ifstartdenotes the position of this truncation or beyond,FALSEwill be returned.If
lengthis given and is 0,FALSEorNULL, an empty string will be returned.If
lengthis omitted, the substring starting fromstartuntil 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"
?>
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'
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
Document créé le 30/01/2003, dernière modification le 26/10/2018
Source du document imprimé : https://www.gaudry.be/php-rf-function.substr.html
L'infobrol est un site personnel dont le contenu n'engage que moi. Le texte est mis à disposition sous licence CreativeCommons(BY-NC-SA). Plus d'info sur les conditions d'utilisation et sur l'auteur.
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