Podręcznik PHP
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# substr

(PHP 3, PHP 4 )

substr -- Return part of a string

## Description

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

substr() returns the portion of `string` specified by the `start` and `length` parameters.

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.

Przykład 1. Basic substr() usage

`<?php $rest = substr("abcdef", 1); // returns "bcdef" $rest = substr("abcdef", 1, 3); // returns "bcd" $rest = substr("abcdef", 0, 4); // returns "abcd" $rest = substr("abcdef", 0, 8); // returns "abcdef" // Accessing via curly braces is another option $string = 'abcdef'; echo $string{0}; // returns a echo $string{3}; // returns d ?>`

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

Przykład 2. Using a negative `start`

`<?php $rest = substr("abcdef", -1); // returns "f" $rest = substr("abcdef", -2); // returns "ef" $rest = substr("abcdef", -3, 1); // returns "d" ?>`

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 `string` is less than `start` characters long, `FALSE` will be returned.

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 a position beyond this truncation, an empty string will be returned.

Przykład 3. 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 "" $rest = substr("abcdef", -3, -1); // returns "de" ?>`

See also strrchr(), substr_replace(), ereg(), trim() and mb_substr().

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substr_replace | Początek rozdziału | trim