What does it mean in c#?

The ? operator (null coalescing operator) in C# is used to provide an alternative value when a variable may be null. The syntax is variableName ?? defaultValue, if variableName is not null, its value is returned, otherwise an alternative value is returned. It provides the advantages of simplicity, readability, and avoidance of null pointer exceptions.

? in C# Operator

in C# The ## operator, also known as the null coalescing operator or the ternary conditional operator, is a concise syntax for providing an alternate value in cases where a variable might be null.

Syntax and usage

? The format of operator usage is:

variableName ?? defaultValue;

• variableName is the variable to check.
• ?? is the null coalescing operator.
• defaultValue is the fallback value returned if variableName is null.

variableName is not null, its value is returned. Otherwise, defaultValue is returned.

Example

? operator:

string name = null;

// 使用 ? 运算符提供备用值
string result = name ?? "Unknown";

Console.WriteLine(result); // 输出 "Unknown"

Advantages

? operator include:

• Simplicity: It provides a concise way to handle possible null variables to avoid lengthy if-else statements.
• Readability: It improves the readability of the code because the behavior of the alternate values ​​is clearly expressed.
• Avoid Null Pointer Exceptions: You can avoid unexpected Null Pointer Exceptions by checking whether a variable is null before accessing it.

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