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45 lines
1.2 KiB
45 lines
1.2 KiB
19 years ago
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<?php
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/**
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* Translates a character position into an 'absolute' byte position.
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* Unit tested by Kasper.
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* (http://phpxref.com/xref/moodle/lib/typo3/class.t3lib_cs.php.source.html.gz)
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*
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* @param string UTF-8 string
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* @param integer Character position (negative values start from the end)
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* @return integer Byte position
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* @author Martin Kutschker <martin.t.kutschker@blackbox.net>
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*/
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function utf8_char2byte_pos($str,$pos) {
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$n = 0; // number of characters found
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$p = abs($pos); // number of characters wanted
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if ($pos >= 0) {
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$i = 0;
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$d = 1;
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} else {
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$i = strlen($str)-1;
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$d = -1;
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}
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for( ; strlen($str{$i}) && $n<$p; $i+=$d) {
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$c = (int)ord($str{$i});
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if (!($c & 0x80)) // single-byte (0xxxxxx)
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$n++;
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elseif (($c & 0xC0) == 0xC0) // multi-byte starting byte (11xxxxxx)
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$n++;
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}
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if (!strlen($str{$i})) return false; // offset beyond string length
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if ($pos >= 0) {
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// skip trailing multi-byte data bytes
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while ((ord($str{$i}) & 0x80) && !(ord($str{$i}) & 0x40)) { $i++; }
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} else {
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// correct offset
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$i++;
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}
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return $i;
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}
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?>
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