[c#] C# "must declare a body because it is not marked abstract, extern, or partial"

I'm not sure why i'm getting this error to be honest.

private int hour
{
    get;
    set
    {
        //make sure hour is positive
        if (value < MIN_HOUR)
        {
            hour = 0;
            MessageBox.Show("Hour value " + value.ToString() + " cannot be negative. Reset to " + MIN_HOUR.ToString(),
                    "Invalid Hour", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
        }
        else
        {
            //take the modulus to ensure always less than 24 hours
            //works even if the value is already within range, or value equal to 24
            hour = value % MAX_HOUR;
        }
    }
}

I've also tried just doing an actual property:

public int hour 
{ 
    get; 
    set
    {
        //make sure hour is positive
        if (value < MIN_HOUR)
        {
            hour = 0;
            MessageBox.Show("Hour value " + value.ToString() + " cannot be negative. Reset to " + MIN_HOUR.ToString(),
                    "Invalid Hour", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
        }
        else
        {
            //take the modulus to ensure always less than 24 hours
            //works even if the value is already within range, or value equal to 24
            hour = value % MAX_HOUR;
        }
    } 
}

Suggestions?

You cannot provide your own implementation for the setter when using automatic properties. In other words, you should either do:

public int Hour { get;set;} // Automatic property, no implementation

or provide your own implementation for both the getter and setter, which is what you want judging from your example:

public int Hour  
{ 
    get { return hour; } 
    set 
    {
        if (value < MIN_HOUR)
        {
            hour = 0;
            MessageBox.Show("Hour value " + value.ToString() + " cannot be negative. Reset to " + MIN_HOUR.ToString(),
                    "Invalid Hour", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
        }
        else
        {
                //take the modulus to ensure always less than 24 hours
                //works even if the value is already within range, or value equal to 24
                hour = value % MAX_HOUR;
        }
     }
}

must declare a body because it is not marked abstract, extern, or partialI had the same problem here:

    private static void swapMth(ref int x, ref int y);
    {
        int num = x;
        x = y;
        y = num;
    }


    private void button_Click(object sender, EventArgs e)
    {
        int x = 10;
        int y = 20;
        labelResult.Text = $"Befor      n1 = {x} , n2={y} ";
        swapMth(ref x, ref y);
        labelResult.Text += $"\n After  n1 = {x} , n2={y}";
    }

And it was solved by deleting ";" from the method line:

private static void swapMth(ref int x, ref int y); PROBLEM

to

private static void swapMth(ref int x, ref int y) SOLVED

I know it is basic mistake, hope someone could get help by this note.

    private static void swapMth(ref int x, ref int y)
    {
        int num = x;
        x = y;
        y = num;
    }


    private void button_Click(object sender, EventArgs e)
    {
        int x = 10;
        int y = 20;
        labelResult.Text = $"Befor      n1 = {x} , n2={y} ";
        swapMth(ref x, ref y);
        labelResult.Text += $"\n After  n1 = {x} , n2={y}";
    }

I got the same error message because I had a function with a parameter named with a reserved word.

   public int SaveDelegate(MyModel.Delegate delegate)

Renaming the variable delegate solved the problem.

You DO NOT have to provide a body for getters and setters IF you'd like the automated compiler to provide a basic implementation.

This DOES however require you to make sure you're using the v3.5 compiler by updating your web.config to something like

 <compilers>
   <compiler language="c#;cs;csharp" extension=".cs" type="Microsoft.CSharp.CSharpCodeProvider,System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" warningLevel="4">
    <providerOption name="CompilerVersion" value="v3.5"/>
    <providerOption name="WarnAsError" value="false"/>
  </compiler>
</compilers>

You can just use the keywork value to accomplish this.

public int Hour {
    get{
        // Do some logic if you want
        //return some custom stuff based on logic

        // or just return the value
        return value;
    }; set { 
        // Do some logic stuff 
        if(value < MINVALUE){
            this.Hour = 0;
        } else {
            // Or just set the value
            this.Hour = value;
        }
    }
}

You need to provide a body for the get; portion as well as the set; portion of the property.

I suspect you want this to be:

private int _hour; // backing field
private int Hour
    {
        get { return _hour; }
        set
        {
            //make sure hour is positive
            if (value < MIN_HOUR)
            {
                _hour = 0;
                MessageBox.Show("Hour value " + value.ToString() + " cannot be negative. Reset to " + MIN_HOUR.ToString(),
                "Invalid Hour", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
            }
            else
            {
                //take the modulus to ensure always less than 24 hours
                //works even if the value is already within range, or value equal to 24
                _hour = value % MAX_HOUR;
            }
        }
    }

That being said, I'd also consider making this code simpler. It's probably is better to use exceptions rather than a MessageBox inside of your property setter for invalid input, as it won't tie you to a specific UI framework.

If that is inappropriate, I would recommend converting this to a method instead of using a property setter. This is especially true since properties have an implicit expectation of being "lightweight"- and displaying a MessageBox to the user really violates that expectation.

You need to either provide a body for both the getter and setter, or neither. Since you have non-trivial logic in your setter, you need a manually-implemented getter like so:

get { return _hour; }

If you decide you don't need the logic in the setter, you could go with an automatically-implemented property like so:

public int Hour { get; set; }