How to Handle Nullable Type Mismatches in Conditional Operator Assignments?

Assign using conditional operators of nullable type

Question:

The compiler encounters a type mismatch error when using conditional operators to assign a value to a nullable type. For example, when trying to assign a nullable integer (EmployeeNumber) to a text box value (employeeNumberTextBox.Text), the error "No implicit conversion between 'null' and 'int'" occurs.

Analysis:

Conditional operators determine the type of an expression based only on the true/false value, regardless of the assignment type. In this case, null and int values ​​result in type ambiguity.

Solution:

To resolve this issue, explicitly convert one of the values ​​to nullable :

<code class="language-csharp">EmployeeNumber =
    string.IsNullOrEmpty(employeeNumberTextBox.Text)
    ? (int?)null
    : Convert.ToInt32(employeeNumberTextBox.Text);</code>

Alternatively, the transformation can be applied to another value:

<code class="language-csharp">EmployeeNumber =
    string.IsNullOrEmpty(employeeNumberTextBox.Text)
    ? null
    : (int?)Convert.ToInt32(employeeNumberTextBox.Text);</code>

Both methods explicitly specify that the return value type of the conditional operator is int? (nullable integer), thus eliminating compiler errors. Which method you choose depends on your coding style preference, both have the same effect.

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