How to Handle Nullable Assignments with Conditional Operators in C#?

Use conditional operators to handle nullable assignments in C#

Nullable type, represented as Nullable<T>, is used to represent a value that may or may not have a valid value. Some developers may encounter challenges with conditional operators when assigning nullable values.

Problems with nullable types and conditional operators

The

conditional operator, usually represented as ?:, evaluates a condition and assigns a different value based on its truth value. However, if one of the assigned values ​​is a nullable type and the other is not, the compiler will generate an error due to type incompatibility.

Consider the following example:

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

Here, EmployeeNumber is Nullable<int>, and employeeNumberTextBox.Text is a string. Assigning null to a nullable type is valid, but converting a string to int is not. The compiler cannot correctly infer the type of expression.

Null coalescing operator is not a viable solution

The

null coalescing operator (??) cannot be used here because a conversion from employeeNumberTextBox.Text to null is required when employeeNumberTextBox.Text is not int.

Convert to nullable type

To solve this problem, any value assigned in the conditional operator must be explicitly converted to a nullable type. This allows the compiler to resolve expression types correctly:

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

or:

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

This allows elegant and concise assignments when using nullable types and conditional operators.

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