[RESOLVED] Passing Nulls

Hi ALL,

I'm using VS2010 C# 4.0.

I have a method declared:

Code:

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public spGetBorderauxLog(String Client, String ProcessDate, Int16? Status, Boolean? Actioned)

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and am attempting to call with the following:

Code:

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...spGetBorderauxLog(drpClient.Text, datepicker.Value == "" ? null : datepicker.Value, drpStatus.SelectedItem.Value == "" ? null : Convert.ToInt16(drpStatus.SelectedItem.Value), null);

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I'm receiving the red line under the following text:

Code:

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null : Convert.ToInt16(drpStatus.SelectedItem.Value)

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Stating Type of conditional expression cannot be determined because there is no implicit conversion between '<null>' and 'short'

I've declared the parameter as nullable, so I cannot see the problem.

Wait, is this resolved?

The type of the parameter that the expression is heading for isn't considered in resolving the type of the expression itself.

The type of a ternary expression is derived from the types of the two return values. The first (null) is of type void (well, that's not exactly a type, but you know what I mean, right?) and the second (Convert.ToInt16(drpStatus.SelectedItem.Value)) is of type int.

int and null are not comparable, therefore that expression is not legal. You need to give the compiler a hint, by casting the null to an 'int?'.

That way you're comparing an 'int?' to an int, which have a common type of 'int?'

Hi,

Although I didn't post my resolution, I needed to cast with Null.

(Int16?)null

So My complete test became.

Code:

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drpStatus.SelectedItem.Value == "" ? (Int16?)null : Convert.ToInt16(drpStatus.SelectedItem.Value)

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