Question

This code throwing out an error:

    bool status1 = (bool)Cache["cache_req_head"];
    bool status2 = (bool)Cache["cache_super"];
    bool status3 = (bool)Cache["cache_head"];

This is how the cache variables were set:

if (checkreqhead == true)
        {
            Cache["cache_req_head"] = true;
        }
        else if (checksuper == true)
        {
            Cache["cache_super"] = true;
        }
        else if (checkhead == true)
        {
            Cache["cache_head"] = true;
        }

Coming from PHP background, this is awkward. The error is:

Object reference not set to an instance of an object

I’m certain it is something really simple, but probably I can’t spot it.

THANKS ALL FOR HELPING 🙂

Answer 1

“Object reference not set to an instance of an object” is c# lingo for “you did something stupid with a null value”

If the Cache is empty you need to check that first

bool status1 = (bool)Cache["cache_req_head"];

should be

bool status1 = false;
if (Cache["cache_req_head"] != null)
{
   status1 = (bool)Cache["cache_req_head"];
}

This is an effect of the fact that value types (like bool, int, etc) in c# can not be null. There is a wrapper, Nullable<T> with the shorthand T? that you can use if you want to allow null values for the value types.

You can cast your value to a bool? since that allows for null.

bool? status1 = (bool?)Cache["cache_req_head"];

You can then check status1 == null or status1.HasValue, to get the actual bool value you need to pick it out with status1.Value. If you pick status1.Value while status1 == null you will get a runtime exception like the one you just got.