C#中的using语句和指令之间有什么区别? [英] What is the difference between the using statement and directive in C#?

问题描述

这基本上是一个教程问题，因为是初学者，我想在我们的C#代码开始使用的using语句(包括程序集和名称空间)之间有什么区别

this is basically a tutorial question to ask since am a beginner I would like to what is a difference between the using statement we use at start of our C# code to include assembly and namespaces

像这样:

using System.Web.Services;

，以及当我们在方法或代码内编写代码时.像这样:

and when we write inside the code within the method or code. like this:

using (SqlDataAdapter adapter = new SqlDataAdapter(cmd))

有什么不同或两者相同，任何指导都会有所帮助和赞赏.

is there any difference or they both are same, any guidance would be helpful and appreciated.

推荐答案

第一个(使用指令)是将命名空间引入范围.

The first (Using Directive) is to bring a namespace into scope.

举例来说，这样您就可以写

This is for example, so you can write

StringBuilder MyStringBuilder = new StringBuilder();

而不是

System.Text.StringBuilder MyStringBuilder = new System.Text.StringBuilder();

---

秒(使用语句)一种用于正确使用(创建和处置)实现 IDisposable的对象界面.

---

The second (Using Statement) one is for correctly using (creating and disposing) an object implementing the IDisposable interface.

例如:

using (Font font1 = new Font("Arial", 10.0f)) 
{
    byte charset = font1.GdiCharSet;
}

在这里， font 类型实现了 IDisposable ，因为它使用了当我们不再使用 Font 实例( font1 )时丢弃.

Here, the Font type implements IDisposable because it uses unmanaged resources that need to be correctly disposed of when we are no-longer using the Font instance (font1).

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