变量在If语句中不起作用

Question

当我发布here时，我设法得到了2个我希望用于进一步处理的变量。不幸的是，我无法使用if if语句。

if (isset($_POST['modifybtn'])) { //Now we have our variables all set
    $SubmissionID = $_POST['modifybtn'];
    $CourseID = $_POST['courseid'];
    }
//We do some irrelevant stuff here.... and then

echo $CourseID; //Works
if (isset($_POST['savebtn'])) {
        echo $CourseID; //Not Working

    saveData($AppID, $CourseID);
    header("Location: applicantCase.php");
}
if (isset($_POST['nextbtn'])) {
    saveData($AppID, $CourseID);
    header("Location: ApplicantApplyEducation.php");
}

为什么会发生这种情况，之前有一行正在发挥作用？

Answer 1

首先，您可以在if条件之外定义。

 $SubmissionID = "";
 $CourseID = "";
if (isset($_POST['modifybtn'])) { //Now we have our variables all set
    $SubmissionID = $_POST['modifybtn'];
    $CourseID = $_POST['courseid'];
    }
//We do some irrelevant stuff here.... and then

echo $CourseID; //Works
if (isset($_POST['savebtn'])) {
        echo $CourseID; //Now it will Working

    saveData($AppID, $CourseID);
    header("Location: applicantCase.php");
}
if (isset($_POST['nextbtn'])) {
    saveData($AppID, $CourseID); // Now it will work
    header("Location: ApplicantApplyEducation.php");
}