C# 的新特性提升了代碼的安全性、簡(jiǎn)潔性和可維護(hù)性。首先，Nullable 引用類(lèi)型通過(guò)編譯時(shí)檢查幫助預(yù)防空引用異常，例如對(duì)可能為null 的變量使用string? 或null-forgiving 操作符。其次，記錄（Records）簡(jiǎn)化了不可變模型的創(chuàng)建，自動(dòng)生成構(gòu)造函數(shù)、屬性和相等性檢查，同時(shí)支持複製修改模式。最後，頂級(jí)語(yǔ)句減少了小型項(xiàng)目的樣板代碼，允許直接編寫(xiě)入口邏輯而無(wú)需顯式Main 方法。這些改進(jìn)使C# 更現(xiàn)代且高效。

C# has been evolving pretty steadily over the past few versions, and if you've been using it for a while, you might have noticed that some of the newer features can really simplify your code or make it more expressive. Let's go through a few key additions in recent versions—like nullable reference types, records, and top-level statements—that are worth getting familiar with.

Nullable Reference Types Help Prevent Null-Related Bugs

Before C# 8, reference types were always nullable by default, which meant you could assign null to them without any warnings. That often led to runtime exceptions if you weren't careful.

Now, with nullable reference types enabled (which they are by default in new projects), the compiler gives you warnings when it thinks you're not handling possible null values correctly.

For example:

 string name = GetName(); // If GetName can return null, this will tr??igger a warning

You can fix this by updating the type to be explicitly nullable:

 string? name = GetName();

And if you're sure the value won't be null, you can use the null-forgiving operator ( ! ) like so:

 string name = GetName()!;

This feature doesn't change runtime behavior—it's all about catching potential issues earlier at compile time.

Records Make Immutable Models Simpler

If you've ever written a class just to hold data—like a DTO or model—you probably wrote a lot of boilerplate: properties, constructors, Equals , GetHashCode , etc. Records , introduced in C# 9, let you cut down on all that.

A basic record looks like this:

 public record Person(string FirstName, string LastName);

That one line gives you:

• A constructor that takes both parameters
• Read-only properties
• Properly implemented equality checks
• A nice ToString() output

You can also make records mutable if needed, but the main point is that they're designed for immutability and value-based equality out of the box.

One thing to note: when you create a new instance using with , it creates a copy:

 var person1 = new Person("John", "Doe");
var person2 = person1 with { LastName = "Smith" };

This makes working with immutable data much easier and less error-prone.

Top-Level Statements Reduce Boilerplate

Starting with C# 9, you can write programs without needing an explicit Main method. This is especially handy for small tools, scripts, or learning purposes.

Instead of writing:

 class Program
{
    static void Main()
    {
        Console.WriteLine("Hello World!");
    }
}

You can now do this:

 Console.WriteLine("Hello World!");

Yes, that's it. The compiler handles the rest behind the scenes. It still generates a Main method, but you don't have to see it unless you need something more complex.

It's great for quick prototypes or simple console apps, but for larger applications, sticking with traditional structure might still be better for clarity and organization.

These features aren't game-changers on their own, but together they make writing and maintaining C# code a bit smoother. Nullable references help avoid common pitfalls, records reduce repetitive code, and top-level statements keep things clean for smaller projects.

基本上就這些。

以上是在最近的C＃版本中探索新的語(yǔ)言功能的詳細(xì)內(nèi)容。更多資訊請(qǐng)關(guān)注PHP中文網(wǎng)其他相關(guān)文章！