HasValue or != null: Which is Better for Checking Nullable Values in C#?

HasValue and != null

for nullable values ​​in C#

C#’s Nullable<t></t> type allows nullable values, which can be valid values ​​or null. To check if a nullable value has been assigned, there are two common ways:

Nullable.HasValue

The

attribute of Nullable<t></t> indicates whether a value has been assigned. It returns a Boolean value that is true if the value is non-null or false if the value is null. HasValue

Nullable != null

This expression also checks whether a nullable value is non-null. It compares nullable values ​​to null using the equals operator.

Equivalence in compilation The

compiler optimizes these checks by replacing

comparisons with calls to != null. This means there is no significant difference in performance or functionality between the two methods. HasValue

Preferences The choice between

and HasValue is purely based on readability and preference. Some developers prefer the unambiguity of != null, while others find the concise HasValue more readable. != null

Example

int? a = null;

// 使用 HasValue
if (a.HasValue)
{
    // ...
}

// 使用 != null
if (a != null)
{
    // ...
}

In summary, both

and HasValue are valid ways to check for non-nullable values ​​in C#. The compiler optimizes these checks to have equivalent behavior, making the choice a matter of developer preference and code readability. != null

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