What is the Purpose of the Question Mark in C# Nullable Types?

C# can be empty type: in -depth understanding of the role of the question mark

Question mark is usually used in conditional sentences, but in C#, it also plays a vital role in indicating the type of empty types.

In C#, the available type (eg,

) using the question mark suffix is ​​a special data type, which can not only represent the valid value of its basic value type, but also indicate the empty value. This function is particularly useful when processing may contain databases or other data sources that are missing or not assigned.

int? myVariable When using the empty type, you can use the

attribute check whether it has assigned the variable. If is true, you can use

attribute to access the actual value. If is fake, the variable is not valid and is considered to be empty. HasValue HasValue For example, consider the following code fragment: Value HasValue

This code shows a MyProperty that can save the integer or empty value. You can assign an effective integer or empty value for this attribute, and you can use the

attribute to check the empty value.

public int? myProperty
{
   get;
   set;
}

The empty type provides security and flexibility when dealing with missing values ​​or not assigning values, because they allow you to clearly indicate the lack of value, without requiring to help special agreed or sentry values.

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