当有多个using语句时，它们会按顺序执行吗？

发布于 2024-10-03 18:20:40 字数 305 浏览 10 评论 0原文

例如，

  using (Stream ftpStream = ftpResponse.GetResponseStream())       // a             
  using (FileStream localFileStream = (new FileInfo(localFilePath)).Create()) // b
  {
                 ........do something
  }

两个语句 a 和 b 会按照我输入的顺序执行吗？并以相同的顺序丢弃？

谢谢

原文

for example

  using (Stream ftpStream = ftpResponse.GetResponseStream())       // a             
  using (FileStream localFileStream = (new FileInfo(localFilePath)).Create()) // b
  {
                 ........do something
  }

will the two statement a and b executed in the order i put?
and displose in the same order as well??

Thanks

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阳光的暖冬 2024-10-10 18:20:40

它们将以文本顺序执行，并以相反的顺序进行处理 - 因此，localFileSream 将首先被处理，然后是 ftpStream。

基本上你的代码相当于：

using (Stream ftpStream = ...)
{
    using (FileStream localFileStream = ...)
    {
        // localFileStream will be disposed when leaving this block
    }
    // ftpStream will be disposed when leaving this block
}

但它比这更进一步。您的代码也与此等效（不考虑不同类型的localFileStream）：

using (Stream ftpStream = ..., localFileStream = ...)
{
    ...
}

They will execute in textual order, and be disposed in reverse order - so localFileSream will be disposed first, then ftpStream.

Basically your code is equivalent to:

using (Stream ftpStream = ...)
{
    using (FileStream localFileStream = ...)
    {
        // localFileStream will be disposed when leaving this block
    }
    // ftpStream will be disposed when leaving this block
}

It goes further than that though. Your code is also equivalent (leaving aside the different type of localFileStream) to this:

using (Stream ftpStream = ..., localFileStream = ...)
{
    ...
}

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始于初秋 2024-10-10 18:20:40

是的。此语法只是嵌套 using 语句的快捷方式或替代方式。您所做的只是省略第一个 using 语句中的括号。它相当于：

using (Stream ftpStream = ftpResponse.GetResponseStream())
{
    using (FileStream localFileStream = (new FileInfo(localFilePath)).Create())
    {
        //insert your code here
    }
}

Yes. This syntax is just a shortcut or alternative way of nesting using statements. All you're doing is omitting the brackets on the first using statement. It's equivalent to:

using (Stream ftpStream = ftpResponse.GetResponseStream())
{
    using (FileStream localFileStream = (new FileInfo(localFilePath)).Create())
    {
        //insert your code here
    }
}

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