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PHP实现截取字符串的通用方法

时间:2021-07-01 10:21:17 帮助过:11人阅读

  1. /**
  2. * 截取字符串
  3. * params $string 要截取的字符串
  4. * params $length: 保留长度(字符数)
  5. * params $dot: 多余部分显示
  6. **/
  7. function _cutstr($string, $length, $dot = ' ...') {
  8. if(strlen($string) <= $length) {
  9. return $string;
  10. }
  11. $string = str_replace(array('&', '"', '<', '>'), array('&', '"', '<', '>'), $string);
  12. $strcut = '';
  13. $n = $tn = $noc = 0;
  14. while($n < strlen($string)) {
  15. $t = ord($string[$n]);
  16. if($t == 9 || $t == 10 || (32 <= $t && $t <= 126)) {
  17. $tn = 1; $n++; $noc++;
  18. } elseif(194 <= $t && $t <= 223) {
  19. $tn = 2; $n += 2; $noc += 2;
  20. } elseif(224 <= $t && $t < 239) {
  21. $tn = 3; $n += 3; $noc += 2;
  22. } elseif(240 <= $t && $t <= 247) {
  23. $tn = 4; $n += 4; $noc += 2;
  24. } elseif(248 <= $t && $t <= 251) {
  25. $tn = 5; $n += 5; $noc += 2;
  26. } elseif($t == 252 || $t == 253) {
  27. $tn = 6; $n += 6; $noc += 2;
  28. } else {
  29. $n++;
  30. }
  31. if($noc >= $length) {
  32. break;
  33. }
  34. }
  35. if($noc > $length) {
  36. $n -= $tn;
  37. }
  38. $strcut = substr($string, 0, $n);
  39. $strcut = str_replace(array('&', '"', '<', '>'), array('&', '"', '<', '>'), $strcut);
  40. return $strcut.$dot;
  41. }

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