PHP English string truncation code sharing _ php instance that can ensure word integrity

This article mainly introduces PHP English strings that can ensure word integrity. The Code contains detailed comments. For more information, see the following code:

/*** Intercept complete words ** @ param $ str * @ param $ start * @ param $ length ** @ return string */public static function usubstr ($ str, $ start, $ length = null) {// You can intercept it again. $ res = substr ($ str, $ start, $ length); $ strlen = strlen ($ str);/* Then judge whether 6 bytes at the beginning and end are complete (not incomplete) * /// if the start parameter is positive, if ($ start> = 0) {// truncates about 6 bytes to the 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 1st byte is not the first byte of the complete character, next, take about 6 bytes. $ prev_start = $ start-6> 0? $ Start-6: 0; $ prev_segm = substr ($ str, $ prev_start, $ start-$ prev_start );} // start is a negative else {// forward and then intercept about 6 bytes $ 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 1st byte is not the first byte of the complete character, next, we can take 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 meet the utf8 Rule if (preg_match ('@ ^ ([x80-xBF] {}) [xC0-xFD]? @ ', $ Next_segm, $ bytes) {if (! Empty ($ bytes [1]) {$ bytes = $ bytes [1]; $ res. = $ bytes ;}/// determine whether the last 6 bytes meet the utf8 rule $ ord0 = ord ($ res [0]); if (128 <= $ ord0 & 191> = $ ord0) {// truncate the image and add it to the front of res. if (preg_match ('@ [xC0-xFD] [x80-xBF] {} $ @', $ prev_segm, $ bytes) {if (! Empty ($ bytes [0]) {$ bytes = $ bytes [0]; $ res = $ bytes. $ res ;}}if (strlen ($ res) <$ strlen) {$ res = $ res. '... ';} return $ res ;}