grapheme_extract()

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

Function to extract a sequence of default grapheme clusters from a text buffer, which must be encoded in UTF-8

说明

过程化风格
grapheme_extract(string $haystack,int $size[,int $extract_type[,int $start= 0[,int &$next]]]): string

Function to extract a sequence of default grapheme clusters from a text buffer, which must be encoded in UTF-8.

参数

$haystack

String to search.

$size

Maximum number items - based on the $extract_type - to return.

$extract_type

Defines the type of units referred to by the $size parameter:

• GRAPHEME_EXTR_COUNT(default)- $size is the number of default grapheme clusters to extract.
• GRAPHEME_EXTR_MAXBYTES -$size is the maximum number of bytes returned.
• GRAPHEME_EXTR_MAXCHARS -$size is the maximum number of UTF-8 characters returned.

$start

Starting position in $haystack in bytes - if given, it must be zero or a positive value that is less than or equal to the length of $haystack in bytes, or a negative value that counts from the end of $haystack. If $start does not point to the first byte of a UTF-8 character, the start position is moved to the next character boundary.

$next

Reference to a value that will be set to the next starting position. When the call returns, this may point to the first byte position past the end of the string.

返回值

A string starting at offset $start and ending on a default grapheme cluster boundary that conforms to the $size and $extract_type specified.

更新日志

范例

grapheme_extract() 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_extract( $char_a_ring_nfd . $char_o_diaeresis_nfd, 1, GRAPHEME_EXTR_COUNT, 2));
?>

以上例程会输出：

o%CC%88

参见

• grapheme_substr()Return part of a string
• » Unicode Text Segmentation: Grapheme Cluster Boundaries

Here's how to use grapheme_extract() to loop across a UTF-8 string character by character.
<?php
$str = "سabcक’…";
// if the previous line didn't come through, the string contained:
//U+0633,U+0061,U+0062,U+0063,U+0915,U+2019,U+2026
$n = 0;
for (  $start = 0, $next = 0, $maxbytes = strlen($str), $c = '';
    $start < $maxbytes;
    $c = grapheme_extract($str, 1, GRAPHEME_EXTR_MAXCHARS , ($start = $next), $next)
  )
{
  if (empty($c))
    continue;
  echo "This utf8 character is " . strlen($c) . " bytes long and its first byte is " . ord($c[0]) . "\n";
  $n++;
}
echo "$n UTF-8 characters in a string of $maxbytes bytes!\n";
// Should print: 7 UTF8 characters in a string of 14 bytes!
?>