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php截取字符串函数,php自定义字符串截取方法

时间:2021-07-01 10:21:17 帮助过:16人阅读

  1. /**
  2. * 方法库-截取字符串
  3. * @param string $string 字符串
  4. * @param int$length 字符长度
  5. * @param string $dot 截取后是否添加...
  6. * @param string $charset编码
  7. * @return string
  8. */
  9. public function cutstr($string, $length, $dot = ' ...', $charset = 'utf-8') {
  10. if (strlen($string) <= $length) {
  11. return $string;
  12. }
  13. $string = str_replace(array('&', '"', '<', '>'), array('&', '"', '<', '>'), $string);
  14. $strcut = '';
  15. if (strtolower($charset) == 'utf-8') {
  16. $n = $tn = $noc = 0;
  17. while ($n < strlen($string)) {
  18. $t = ord($string[$n]); //ASCII?
  19. if($t == 9 || $t == 10 || (32 <= $t && $t <= 126)) {
  20. $tn = 1; $n++; $noc++;
  21. } elseif (194 <= $t && $t <= 223) {
  22. $tn = 2; $n += 2; $noc += 2;
  23. } elseif (224 <= $t && $t < 239) {
  24. $tn = 3; $n += 3; $noc += 2;
  25. } elseif (240 <= $t && $t <= 247) {
  26. $tn = 4; $n += 4; $noc += 2;
  27. } elseif (248 <= $t && $t <= 251) {
  28. $tn = 5; $n += 5; $noc += 2;
  29. } elseif ($t == 252 || $t == 253) {
  30. $tn = 6; $n += 6; $noc += 2;
  31. } else {
  32. $n++;
  33. }
  34. if($noc >= $length) {
  35. break;
  36. }
  37. }
  38. if ($noc > $length) {
  39. $n -= $tn;
  40. }
  41. $strcut = substr($string, 0, $n);
  42. } else {
  43. for ($i = 0; $i < $length; $i++) {
  44. $strcut .= ord($string[$i]) > 127 ? $string[$i].$string[++$i] : $string[$i];
  45. }
  46. }
  47. $strcut = str_replace(array('&', '"', '<', '>'), array('&', '"', '<', '>'), $strcut);
  48. return $strcut.$dot;
  49. }

例2,php检测字符串是否存在:

  1. /**
  2. * 方法库-字符串是否存在
  3. * @param string $str :字符或字符串
  4. * @param string $string :字符串
  5. * @return string 例子: $str='34' $string='1234' 返回 TRUE
  6. */
  7. public function is_str_exist($str, $string) {
  8. $string = (string) $string;
  9. $str = (string) $str;
  10. return strstr($string,$str)===false ? false : true;
  11. }

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