php - 解析错误: syntax error, unexpected '$os' (T_VARIABLE) PHP Error

Question

我正在使用以下代码来尝试并打印用户的操作系统:

header :

<?php
$user_agent = getenv("HTTP_USER_AGENT");

if (strpos($user_agent, "Win") !== FALSE)
$os = "Windows"; 
else (strpos($user_agent, "Mac") !== FALSE)
$os = "Mac";
?>

body :

<?php
if($os = "Windows")
{

}
elseif($os == "Mac")
{

} 
?>

我得到错误

Parse error: syntax error, unexpected '$os' (T_VARIABLE) in C:\xampp\xamppfile\htdocs\ProjectSite\includes\identifier.php on line 7

Answer 1

<?php
$user_agent = getenv("HTTP_USER_AGENT");

if (strpos($user_agent, "Win") !== FALSE) {
    $os = "Windows"; 

}
else if(strpos($user_agent, "Mac") !== FALSE) {
    $os = "Mac";
}

?>