grapheme_extract
(PHP 5 >= 5.3.0, PECL intl >= 1.0.0)
grapheme_extract — Function to extract a sequence of default grapheme clusters from a text buffer, which must be encoded in UTF-8.
Description
Procedural style
$haystack
, int $size
[, int $extract_type
[, int $start = 0
[, int &$next
]]] )Function to extract a sequence of default grapheme clusters from a text buffer, which must be encoded in UTF-8.
Parameters
-
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. 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.
Return Values
A string starting at offset $start and ending on a default grapheme cluster boundary that conforms to the $size and $extract_type specified.
Examples
Example #1 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));
?>
The above example will output:
o%CC%88
See Also
- grapheme_substr() - Return part of a string
- » Unicode Text Segmentation: Grapheme Cluster Boundaries
Коментарии
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!
?>
Looping through grapheme clusters:
<?php
// Example taken from Rust documentation: https://doc.rust-lang.org/book/ch08-02-strings.html#bytes-and-scalar-values-and-grapheme-clusters-oh-my
$str = "नमस्ते";
// Alternatively:
//$str = pack('C*', ...[224, 164, 168, 224, 164, 174, 224, 164, 184, 224, 165, 141, 224, 164, 164, 224, 165, 135]);
$next = 0;
$maxbytes = strlen($str);
var_dump($str);
while ($next < $maxbytes) {
$char = grapheme_extract($str, 1, GRAPHEME_EXTR_COUNT, $next, $next);
if (empty($char)) {
continue;
}
echo "{$char} - This utf8 character is " . strlen($char) . ' bytes long', PHP_EOL;
}
//string(18) "नमस्ते"
//न - This utf8 character is 3 bytes long
//म - This utf8 character is 3 bytes long
//स् - This utf8 character is 6 bytes long
//ते - This utf8 character is 6 bytes long
?>
The other comments on this page were helpful for me.However, consider using something better than empty($value) when checking the value returned by grapheme_extract since it could as well return something like "0" (which of course evaluates to false).