获取解析错误，PHP代码中的语法错误[重复]

Question

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• PHP parse/syntax errors; and how to solve them? 17 answers
• When to use single quotes, double quotes, and backticks in MySQL 12 answers

I am getting this message

Parse error: syntax error, unexpected '$username' (T_VARIABLE) in C:\wamp64\www\tutorialegister_parse.php on line 9

when trying my own register for forum. I can figure out what ive done wrong. here is the code:

<?php 
include("connect.php");

$username = $_POST["username"];
$password = $_POST["password"];

$sql = "INSERT INTO forum.users(username,password)
VALUES("$username","$password"); ";
$res = mysql_query($sql);

if($res){
echo "Successfully registered as: ".$username;

}
else{
echo "failed to register, please try again </br>";
echo "ERROR: ".mysql_error();
}

?>

</div>