字符串

 <?php
  #取得字符串中个某个字符
  #{}可以区分是字符串索引和数组索引
  $str = 'Take me to your heart. Take me to your soul.';
  echo $str[3];
  echo $str{3};
  
  #查找子字符串 找到返回其实位置的数值下标，否则返回false
  echo strpos($str,'@');
  
  #提取子字符串
  echo substr($str,0,5);
  
  #替换子字符串
  echo substr_replace($str,'god',11);
  
  #翻转字符串的顺序
  echo strrev($str)
 ?>