A function that truly intercepts strings according to the rules of utf8 encoding (utf8 version sub_str)_PHP tutorial

Copy code The code is as follows:

/*
* Function: The function is the same as substr, except that it will not cause garbled characters
* Parameters:
* Return:
*/
function utf8_substr( $str , $start , $length=null ){
// Intercept normally first.
$res = substr ( $str , $start , $length );
$strlen = strlen( $str );
/* Then determine whether the first and last 6 bytes are complete (not incomplete) */
// If The parameter start is a positive number
if ( $start >= 0 ){
//Truncate about 6 bytes forward
$next_start = $start + $length; // Initial position
$ next_len = $next_start + 6 <= $strlen ? 6 : $strlen - $next_start;
$next_segm = substr( $str , $next_start , $next_len );
// If the first byte is not The first byte of the complete character, and then intercept about 6 bytes
$prev_start = $start - 6 > 0 ? $start - 6 : 0;
$prev_segm = substr( $str , $prev_start , $start - $prev_start );
}
// start is a negative number
else{
// intercept about 6 bytes forward
$next_start = $strlen + $start + $ length; // Initial position
$next_len = $next_start + 6 <= $strlen ? 6 : $strlen - $next_start;
$next_segm = substr( $str , $next_start , $next_len );
// If the first byte is not the first byte of the complete character, then intercept about 6 bytes.
$start = $strlen + $start;
$prev_start = $start - 6 > 0 ? $start - 6 : 0;
$prev_segm = substr( $str , $prev_start , $start - $prev_start );
}
// Determine whether the first 6 bytes comply with utf8 rules
if ( preg_match( '@^([x80-xBF]{0,5})[xC0-xFD]?@' , $next_segm , $bytes ) ){
if ( !empty( $bytes[1] ) ){
$bytes = $bytes[1];
$res .= $bytes;
}
}
// Determine whether the last 6 bytes comply with utf8 rules
$ord0 = ord( $res[0] );
if ( 128 <= $ord0 && 191 >= $ord0 ){
// Intercept from the back and add it in front of res.
if ( preg_match( '@[xC0-xFD][x80-xBF]{0,5}$@' , $prev_segm , $bytes ) ){
if ( !empty( $bytes[0] ) ){
$bytes = $bytes[0];
$res = $bytes . $res;
}
}
}
return $res;
}

Test data::

Copy code The code is as follows:

$ str = 'dfjdjf test 13f test 65&2 data fdj (1 on mfe&...on';
var_dump( utf8_substr( $str , 22 , 12 ) ); echo '
';
var_dump( utf8_substr( $str , 22 , -6 ) ); echo '
';
var_dump( utf8_substr( $str , 9 , 12 ) ); echo '
';
var_dump( utf8_substr( $str , 19 , 12 ) ); echo '
';
var_dump( utf8_substr( $str , 28 , -6 ) ); echo '
' ;

Display results:: (No garbled interception, everyone is welcome to test and submit bugs)
string(12) "According toｆｽdｊ"
string(26) "According toｆｽdｊ（1 mfe&…"
string(13) "13f try 65&2 number"
string(12) "Dataｆｄ"
string(20) "dｊ（1 is mfe&…"

http://www.bkjia.com/PHPjc/326195.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/326195.htmlTechArticleCopy code The code is as follows: /* * Function: The function is the same as substr, except that it will not cause garbled characters* Parameters: * Return: */ function utf8_substr( $str , $start , $length=null ){ // First cut normally...