String is null and not identifiable

You can use the below statement

if (!string.IsNullOrWhiteSpace(Course))

{

//write here your code

}

Simply use string.IsNullOrEmpty(Course) to validate null or empty.

if (Course != null && Course != "" && Course != "null")
{
    // Your code here
}

In this corrected condition, the if statement will only be true if all three conditions are true:

1. Course != null - This part checks if Course is not null.
2. Course != "" - This part checks if Course is not an empty string.
3. Course != "null" - This part checks if Course is not the string "null".

try this
 

if (!string.IsNullOrEmpty(Course))
{

}

Hello,

You can use below to check string is null or empty, string just we need to use inbuilt method which will check string is null or empty.

if (!string.IsNullOrEmpty(Course))
{
	// Your code here
}

if you want to show string as empty then you can assign,

var Course = string.Empty;

Because you're using the OR (||) operator, if any of these conditions is true, the entire expression will be true. So, even if Course is null, the first condition will be true and the entire condition will be true.

To fix this, you should use the AND (&&) operator instead of the OR (||) operator:

if (Course != null && !Course.equals("") && !Course.equals("null")) {
    // Your code here
}

Try below,

if (!string.IsNullOrEmpty(Course) && !Course.Equals("null"))
{
	// Your code here
}

Thanks

Based on what you've described, if you are directly checking if (Course != null) and still encountering unexpected behavior where the condition evaluates to true when Course is null, there might be some other issue in your code or environment.

I have used only one like if(Course !=null) still same result 

Also I have tried if(Course!="") still same 

Also I have tried  if(Course!="null") still same my actual value of course is null when I hover the mouse on that variable its value is null

In your condition, you're using the logical OR (||) operator, which means that if any one of the conditions is true, the whole expression will evaluate to true. Since you're checking for different conditions using OR operators, at least one of them will always be true, which is why your if condition is always true.

if (Course != null && Course != "")
{
    // Your code here
}