php中输出变量加大括号{}作用

<?php

header("Content-Type:text/html; charset=utf-8");

$test="1变量1";

//echo "前面有字符串aa ".$test." bb后面字符串";

echo "前面有字符串aa {$test} bb后面字符串";

?>

$str = 'hello';
echo $str{0}; // 输出为 h
echo $str{1}; // 输出为 e

if ( !isset ( $str{5} ) ) 就比 if ( strlen ( $str ) < 5 ) 好。

 <?php echo $_SERVER["HTTP_USER_AGENT"];?>

<?php
if(strpos($_SERVER["HTTP_USER_AGENT"],"MSIE 9.0"))
echo "Internet Explorer 9.0";
else if(strpos($_SERVER["HTTP_USER_AGENT"],"MSIE 8.0"))
echo "Internet Explorer 8.0";
else if(strpos($_SERVER["HTTP_USER_AGENT"],"MSIE 7.0"))
echo "Internet Explorer 7.0";
else if(strpos($_SERVER["HTTP_USER_AGENT"],"MSIE 6.0"))
echo "Internet Explorer 6.0";
else if(strpos($_SERVER["HTTP_USER_AGENT"],"Firefox"))
echo "Firefox";
else if(strpos($_SERVER["HTTP_USER_AGENT"],"Chrome"))
echo "Chrome";
else if(strpos($_SERVER["HTTP_USER_AGENT"],"Safari"))
echo "Safari";
else if(strpos($_SERVER["HTTP_USER_AGENT"],"Opera"))
echo "Opera";
else echo $_SERVER["HTTP_USER_AGENT"];
?>

else if(strpos($_SERVER["HTTP_USER_AGENT"],"Opera"))

替换成

else if(strpos($_SERVER["HTTP_USER_AGENT"],"pera"))

function my_get_browser(){
 if(empty($_SERVER['HTTP_USER_AGENT'])){
  return '命令行，机器人来了！';
 }
 if(false!==strpos($_SERVER['HTTP_USER_AGENT'],'MSIE 9.0')){
  return 'Internet Explorer 9.0';
 }
 if(false!==strpos($_SERVER['HTTP_USER_AGENT'],'MSIE 8.0')){
  return 'Internet Explorer 8.0';
 }
 if(false!==strpos($_SERVER['HTTP_USER_AGENT'],'MSIE 7.0')){
  return 'Internet Explorer 7.0';
 }
 if(false!==strpos($_SERVER['HTTP_USER_AGENT'],'MSIE 6.0')){
  return 'Internet Explorer 6.0';
 }
 if(false!==strpos($_SERVER['HTTP_USER_AGENT'],'Firefox')){
  return 'Firefox';
 }
 if(false!==strpos($_SERVER['HTTP_USER_AGENT'],'Chrome')){
  return 'Chrome';
 }
 if(false!==strpos($_SERVER['HTTP_USER_AGENT'],'Safari')){
  return 'Safari';
 }
 if(false!==strpos($_SERVER['HTTP_USER_AGENT'],'Opera')){
  return 'Opera';
 }
 if(false!==strpos($_SERVER['HTTP_USER_AGENT'],'360SE')){
  return '360SE';
 }
}

<?php     echo $_GET['para']; ?>

<?php     include 'http://www.yoururl.com/inc.php?para=3'; ?>

<?php
//注销cookie
if(isset($_GET['out'])){
setcookie('us',"");
echo "<script>location.href='index.php'</script>";
}

//设置cookie
if(isset($_POST['sub'])){
setcookie("us",$_POST['user'],time()+3600);
echo "<script>location.href='index.php'</script>";
}

//输出和注销cookie
if($_COOKIE['us']){
echo $_COOKIE['us'];
echo "<a href='index.php?out=out'>注销cookies</a>";
}

?>
<form method="post">
<input type="text" name="user">
<input type="password" name="pass">
<input type="submit" name="sub" value="提交">
</form>