substr_replace
trim
String Funkcje
PHP Manual

# substr

(PHP 4, PHP 5)

substr — Return part of a string

### Opis

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

Returns the portion of `string` specified by the `start` and `length` parameters.

### Parametry

`string`

  The input string. Must be one character or longer.

`start`

  If `start` is non-negative, 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 `start` is negative, the returned string will start at the `start`'th character from the end of `string`.

  If `string` is less than or equal to `start` characters long, `FALSE` will be returned.

  Przykład #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 most `length` characters beginning from `start` (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 `start` is negative). If `start` 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 `start` until the end of the string will be returned.

  Przykład #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"
  ?>`

### Zwracane wartości

Returns the extracted part of string; lub `FALSE` w przypadku niepowodzenia, or an empty `string`.

### Rejestr zmian

Wersja | Opis
--- | ---
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.

### Przykłady

Przykład #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
?>`

Przykład #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;
?>`

Powyższy przykład wyświetli:

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

### Błędy/Wyjątki

Returns `FALSE` on error.

`<?php
var_dump(substr('a', 1)); // bool(false)
?>`

### Zobacz też:

- strrchr() - Znajduje ostatnie występowanie znaku w łańcuchu znaków
- substr_replace() - Zastępuje tekst wewnątrz części łańcucha
- 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() - Zawija łańcuch znaków po podanej liczbie znaków używając znaku łamania łańcucha.
- String access and modification by character

substr_replace
trim
String Funkcje
PHP Manual