在Fortran中内联读取的含义是什么? [英] What's the meaning of an inline read in Fortran?

问题描述

我在一段代码中发现了这个奇怪的语句:

I have found this weird statement in a piece of code:

read(10, *) ((matrix(i, j), i=1, n), j=m, 1, -1)

我想知道这种内联递归阅读是如何工作的.是什么意思 ((matrix(i, j), i=1, n), j=m, 1, -1)?

I am wondering how this inline recursive reading works. What is the meaning of ((matrix(i, j), i=1, n), j=m, 1, -1)?

推荐答案

这不是在线递归阅读(不确定您从何处获得此术语)，这是一个示例嵌套的暗示执行循环，请参见此处，例如，表示隐式do循环的语法以及这些示例的许多示例.基本上，隐式的do循环是一种在一行上编写do循环的方法.使用嵌套的隐式do循环，您可以在一行上编写多个do循环.

This is not an in-line recursive read (not sure where you got this term from), this is an example of a nested implied do loop, see here, for example, for the syntax of an implied do loop and many examples of these in action. Basically an implied do loop is a way to write a do loop on a single line. With nested implied do loops you can write multiple do loops on a single line.

在您的情况下，您所拥有的等同于(请注意，如果OP应注意任何差异，请在此处更正我)类似的东西(请注意，我已经从外循环向内解开了隐式的do循环) :

In your case, what you have is equivalent to (someone please correct me here if there there are any differences the OP should be aware of) something like (notice that I have unravelled the implied do loop from the outer loop inwards):

integer, parameter :: n=<some-value>
integer, parameter :: m=<some-value>
<some-type>, dimension(n,m) :: matrix

integer :: i, j

do j = m,1,-1
  do i = 1,n
      read(10,*) matrix(i,j)
  end do
end do

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