Checking null variable error

[Avash]

bool empty;
if (empty == null){
//do something
}

Use of unassigned local variable.
This doesn’t make any sense. How do I fix this?

[tanoshimi]

What doesn’t make any sense? empty is unassigned, as the error message states. You fix it by assigning a value to the variable, which can either be on the same line as the declaration, or any time before it is used.

Since bool is not a nullable type, you must either assign it the value true or false:

bool empty = false;
if (empty == false){
    //do something
}

Or, if you’re using a nullable type such as a string, you could assign a null value as follows:

string empty = null;
if (empty == null){
    //do something
}

[Lex_87]

Boolean is value type in .NET FCL type library. Value types hasn’t null state. In C# idiomas you have to initialize local variables, then use them in the same context. Except that cases where you guaranteed take a value through ref keyword. In this case local variable initialization will be redundant. As Tanoshimi says you can initialize first and use them safe below.