php函数练习（substr rtrim ltrim）

1、下面的字符串是5个邮箱地址，要求输出每个邮箱的用户名。

字符串如下：

lili@162.com,tom@163.com,18765231@qq.com,jack@sina.com,wang@162.com

答案：

<?php 

  $str = "&& 明日编程词典 &&";

  $str1 = trim(trim($str,"&&"));

  echo "---".$str1."--";

  echo strlen($str1);

  //rtrim(ltrim($str,"&& ")," &&")

  echo "<hr>";

  $s="At the beginning of the new year, I wish you a happy New Year";

  $s1 = strtolower($s);

  echo substr_count($s1,"new year");

  echo "<br>";

  echo str_ireplace("new year","@",$s);

?>

2、去除字符串“&& 明日编程词典 &&”首尾空格和特殊字符&&，并计算剩下字符串的长度。

在字符串“At the beginning of the new year, I wish you a happy New Year”，检索“new year”出现的次数（不区分大小写），然后把“new year”替换成"@"。

<?php 

  $str = "&& 明日编程词典 &&";

  $str1 = trim(trim($str,"&&"));

  echo "---".$str1."--";

  echo strlen($str1);

  //rtrim(ltrim($str,"&& ")," &&")

  echo "<hr>";

  $s="At the beginning of the new year, I wish you a happy New Year";

  $s1 = strtolower($s);

  echo substr_count($s1,"new year");

  echo "<br>";

  echo str_ireplace("new year","@",$s);

?>

基本的函数，多加练习熟能生巧。