grapheme_substr

(PHP 5 >= 5.3.0, PHP 7, PHP 8, PECL intl >= 1.0.0)

grapheme_substr — Return part of a string

说明

过程化风格

grapheme_substr(string $string, int $offset, ?int $length = null): string|false

Return part of a string

参数

string: The input string. Must be valid UTF-8.
offset: Start position in default grapheme units. If offset is non-negative, the returned string will start at the offset'th position in string, counting from zero. If offset is negative, the returned string will start at the offset'th grapheme unit from the end of string.
length: Length in grapheme units. If length is given and is positive, the string returned will contain at most length grapheme units beginning from offset (depending on the length of string). If length is given and is negative, then that many grapheme units will be omitted from the end of string (after the start position has been calculated when offset is negative). If offset denotes a position beyond this truncation, an empty string will be returned.

返回值

Returns the extracted part of string, 或者在失败时返回 false.

更新日志

版本	说明
8.0.0	The function now consistently clamps out-of-bounds offsets to the string boundary. Previously, `false` was returned instead of the empty string in some cases.

示例

示例 #1 grapheme_substr() example

<?php

$char_a_ring_nfd = "a\xCC\x8A";  // 'LATIN SMALL LETTER A WITH RING ABOVE' (U+00E5) normalization form "D"
$char_o_diaeresis_nfd = "o\xCC\x88"; // 'LATIN SMALL LETTER O WITH DIAERESIS' (U+00F6) normalization form "D"

print urlencode(grapheme_substr( "ao" . $char_a_ring_nfd . "bc" . $char_o_diaeresis_nfd . "O", 2, -1 ));
?>

以上示例会输出：

a%CC%8Abco%CC%88

参见

grapheme_extract() - Function to extract a sequence of default grapheme clusters from a text buffer, which must be encoded in UTF-8
» Unicode Text Segmentation: Grapheme Cluster Boundaries

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