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Value Assigned Is Not Used

I may be overlooking something, well obviously I am. I am using an uninitialized variable of type int (carRequired). I am utilizing this variable inside an IF statement (code below). However, I get a warning stating the variable is never used yet it is. Yes, I am aware of not being good practice to embed sql, however I am told to do it this way for now.
public bool UpdateDiscrepancyReport()
{
var errorStatus = false;
int carRequired ;
carRequired = cbxCarRequired.Checked == false ? 0 : 1;
var updateQuery = "my query string ";
dbf.OpenConnection(updateQuery);
bool updateStatus = dbf.OpenConnection(updateQuery);
if (updateStatus)
{
errorStatus = true;
}
else
{
MessageBox.Show(#"Error in updating DR" + tbxDRNumber.Text+#" ",#"Update Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
return errorStatus;
}

The variable is never used. It is assigned to, but the variable is never used after that assignment; you don't do anything after assigning the result of the ternary operation to it. In fact, the variable isn't necessary at all, and neither is errorStatus (in the original code you posted), since you never do anything in the code that will change it's value after it is initialized.
The code you've posted (prior to your edit that added several more lines) is the exact equivalent of
public bool UpdateDiscrepancyReport()
{
dbf.OpenConnection(updateQuery);
return false;
}
The compiler is telling you that the variable declaration and assignment to carRequired is meaningless, because it does not affect anything in your code. Determining whether the checkbox is checked or not only has meaning if your code does something differently based on that information, and the use of carRequired as written does nothing based on the value assigned; therefore, the assignment (and variable declaration) are useless.

How can I get the default value of a field in a class in C#?

Say I have my class, and I have the non-static variable
int x = 5;
After the code runs x is changed to something else, how can I get the value x started with using reflection?

Short answer: you can't.
If you implement some kind of custom transactional system, than it is possible. Out of the box: no luck.
And yes, the custom transactional system can be very simple: add another field or property that you use to 'remember' the initial value.

if i understand you correctly you want the initial value of the x.
for that you need another member or parameter to keep the first initializing of x. for example in your class:
int FirstX = -1;// or any other value you know ain't gonna come
bool firstInitial = true;
public int X
{
set
{
if(firstInitial)
{
FirstX = value;
firstInitial = false;
}
x = value
}
}

Now if you mean default value that is set at class level, you already know as it is constant other way would be creating an instance of the class for which you need default value.
ClassName className= new ClassName();
className.MyProp//This will always give default value.
new ClassName().MyProp //would also do.
If you want list of transactional values you need to implement it, reflection is not meant for that.

How to tell if an out parameter was set already?

Is there a way to know if an out parameter was set already or not. This is the pseudocode for what I am looking for:
public virtual string blabla(long num, out bool bval)
{
if (!bval.HasValue)
{
//Do some default logic
bval = defaultValue;
}
return blabla2(num, bval);
}

You can't - you can't read the variable until it's been definitely assigned within your method. You should think of it as being like a local variable, declared but not assigned any value at the start of the method - but which you must assign a value to before you return. (It's okay not to have assigned a value to it if an exception is thrown.)
If you want a parameter which carries information as input to the method as well as propagating information out, you should use ref instead of out.
See my article on parameter passing for more information.

In addition to Jon's excellent answer, if you want the parameter to still be out, but need to see if it has been assigned a value at some place inside the method, you could use a local nullable type like follows:
public virtual string blabla(long num, out bool bval)
{
bool? bvalLocal;
... //I'm assuming there is some code here that may or
//may not assign bvalLocal?
// This whole if block may not be needed if the default
// value is the default for the type (i.e. false) as
// GetValueOrDefualt() will take care of that (see
// second to last line).
if (!bvalLocal.HasValue)
{
//Do some default logic
bvalLocal = defaultValue;
}
bval = bvalLocal.GetValueOrDefault();
return blabla2(num, bval);
}

Question about compilation error related to a use in the keyword/reserved word "out"

Hello
I'm having an error with this code:
"The out parameter 'o_BlockingSquaresArr' must be assigned to before control leaves the current method"
Now this error paints each return statement of each method apart from the last one with red..
I don't understand what is the problem regarding my specific code
Please help me,
Thanks in Advance
internal bool isLegalMove(Square i_Move, out List<Square> o_BlockingSquaresArr)
{
bool result;
if (m_GameBoard[i_Move.RowIndex, (int)i_Move.ColIndex].Coin != null)
{
result = false;
m_MessageBuffer = "You have enterd a square which is already
occupied, please try again...";
m_ErrorFlag=true;
}
else
{
result = checkIfThereIsAtLeastOneSeqInOneDirection(i_Move,out o_BlockingSquaresArr);
}
return result;
}
internal bool checkIfThereIsAtLeastOneSeqInOneDirection(Square i_Move, out List<Square> o_BlockingSquaresArr)
{
const int k_EightDirections = 8;
bool isSequenceFound, finalRes = false;
for (int i = 1; i <= k_EightDirections; i++)
{
isSequenceFound = checkOpponentSequenceInDirection(i_Move, (eDirections)i, out o_BlockingSquaresArr);
if (isSequenceFound)
{
finalRes = true;
}
}
return finalRes;
}
internal bool checkOpponentSequenceInDirection(Square i_Move, eDirections i_Direction, out List<Square> o_BlockingSquaresArr)
{
//I've shortened this code only relevant things
Square o_AdjacentSquare = new Square();
adjacentCoin = doSwitchAndRetrieveAdjacentCoin(i_Move, i_Direction, out o_AdjacentSquare);
// ...
if (isThereAnOpponentSequence)
{
o_BlockingSquaresArr.Add(o_AdjacentSquare);
}
return isThereAnOpponentSequence;
}

As the compiler error says, an out parameter has to be definitely assigned before any non-exceptional return of a method. I can't see any assignment to o_BlockingSquaresArr anywhere. Why are you even declaring it as an out parameter to start with?

An out parameter must be assigned a value before the method returns. In your isLegalMove method, o_BlockingSquaresArr is only assigned in the else block, so the compiler detects there are some cases where it is not initialized. You must make sure that all code paths in the method assign a value to o_BlockingSquaresArr before returning

You need to assign something to the out parameter in every execution path. In your case, you forget that in one case. Simply assign a default value of the beginning of the method so you don't run into it.
I can't tell you where as you didn't include the method name it is happening in.

In the IsLegalMove function, you need to assign a value to the o_BlockingSquaresArr variable

You need to assign something to out parameters in every (normally terminating) codepath. And you don't do that.
For example in some functions you only assign to the parameter inside the for-loop. And if the loop has 0 iterations this will never happen.

what value will have property of my object?

Hi in my opinion property of my object shouold be 2, but after this code, is still 1, why?
internal class Program
{
private static void Main(string[] args)
{
MyClass value = new MyClass() { Property = 1 };
value.Property = value.Property++;
Console.WriteLine(value.Property);
Console.ReadKey();
}
}
internal class MyClass
{
public int Property;
}
in my opinion this should value.Property = value.Property++; first put to value what is in value and the increment property of this object, why id doesn't work?

What this does is:
Evaluate value.Property on the right hand side (result is 1) and remember the result
Increment value.Property (now it's equal to 2)
Assign the remembered result to value.Property (it's now again equal to 1!)
If you change Property to a property with an explicit getter and setter and put some debugging code inside the setter, you will see that it does indeed change values 1 -> 2 -> 1.
If you changed value.Property++ to ++value.Property, the first two steps would be reversed, so we 'd have:
Increment value.Property (now it's equal to 2)
Evaluate value.Property on the right hand side (it's still 2)
Assign the result of step 2 to value.Property (it's still 2)
Of course, this is unnecessarily complicated and one could even say, wrong. If you want to increment Property, all you have to do is this:
++value.Property;

Because valueProperty++ is the same as the following:
int Increment(ref int value)
{
var temp = value;
value = value + 1;
return temp;
}

value.Property = value.Property++;
Here value.Property++ means it assing 1 before incrementing.

Because the = operator is lower down the order of operator precedence than increment.
http://msdn.microsoft.com/en-us/library/6a71f45d.aspx <- shows al the operators and their order of precedence.
The increment gets evaluated first completely. then the returned value from the increment is put through the = operator.