请说明int a之间是否有任何区别;和int a = new int（） [英] please explain if there is any difference between int a; and int a =new int()

问题描述

hi expert





C＃中的以下声明之间有什么区别吗？



int a;



int a = new int（）;





请解释。



谢谢和问候

Divaker

hi expert


Is there any difference between following statement in C#?

int a;

int a=new int();


please explain.

Thanks & Regards
Divaker

推荐答案

行

The line

int a;

声明 int 变量 a 。它必须在使用前初始化。



行

declares the int variable a. It must be initialized before use.

The line

int a=new int();

声明并初始化为 0 int 变量 a 。



参见值类型（C＃参考） [ ^ ]。

见这里 [ ^ ]



我的猜测是新的int（）将生成一个0和int a（没有new）将生成一些奇怪的值，如int max或int min值。



创建一个控制台应用程序并尝试将其打印出来。

See here[^]

my guess is that new int() will generate a 0 and int a (without new) will generate some weird value like int max or int min values.

Create a console application and try to print it out.

class Program {
    static void Main(string[] args) {
        int a;
        int b = new int();
        Console.WriteLine("a = " + a);
        Console.WriteLine("b = " + b);
        Console.ReadLine();
    }
}

试过它，甚至不编译。 a未初始化，因此您无法使用它。你需要在使用之前设置一个值。

Just tried it, doesn't even compile. a is uninitialized so you can't use it. You need to set a value before using a.

int a;: allocates an int on stack and does not initialize it.
int a=5;: allocates an int on stack and sets it to 5;
int a=new int();: allocates an int on stack and sets it to 0;
int a=new int(5);: does not compile.

或





你可以看到第二个只是初始化它，第一个初始化和设置。至于生成的IL代码，它们都在一行中初始化

OR


As you can see second one just initialize it and first one initialize and set . As for the IL code generated, they both get initialized in a single line

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