*在Fortran输入/输出中的用途是什么 [英] What is the purpose of * in Fortran input/output

问题描述

我正在学习Fortran，因为我认为我会学习它。然而，我完全没有发现打印，阅读等目的*的信息：

 程序main 
 
 print *，你好，世界！ 
 
 end program main 
  

这个<$ c $的目的是什么C> * ？我已经做了一些研究，但我认为我没有正确理解，我不想继续学习，直到我真正知道 * 的要点。

从我设法找到的我认为它是某种格式说明符，然而，我不明白这意味着什么，我不知道我是否甚至正确。我找到的所有教程都告诉我要写什么来打印到控制台，但不是 * 实际上意味着什么。

解决方案

您正确的是它是一个格式说明符。

Wikibooks上有一个关于 IO 并表明：

第二个*指定用户希望在中使用

读取的格式的格式>读取语句。这也适用于 write 和 print 语句。

对于固定点实数：Fw.d; w是分配给该数字的空间总数，d是小数位数。

他们给出的例子是

  REAL :: A 
 READ（*，'（F5.2）'）A 
  

读取小数点前后两位数的实数。因此，如果您打印的是实际的号码，您可以使用：

  PRINT'（F5.2）'，A 
  

得到四舍五入的输出结果。

你只是打印文本，所以没有特殊的格式。另外，如果您将格式说明符保留为 * ，它会将默认格式应用于reals等。

I am learning Fortran because well, yeah, thought I'd learn it. However, I've found utterly no information on what the purpose of * is in print, read, etc:

program main

    print *, "Hello, world!"

end program main

What is the purpose of this *? I've done some research however I don't think I understand it properly, I don't want to carry on learning until I actually know the point of *.

From what I've managed to find I think that it's some sort of format specifier, however, I don't understand what that means and I have no idea if I'm even correct. All the tutorials I've found just tell me what to write to print to the console but not what * actually means.

解决方案

You are correct in that it is a format specifier.

There's a page on Wikibooks to do with IO and that states:

The second * specifies the format the user wants the number read with

when talking about the read statement. This applies to the write and print statements too.

For fixed point reals: Fw.d; w is the total number of spaces alloted for the number, and d is the number of decimal places.

And the example they give is

REAL :: A
READ(*,'(F5.2)') A

which reads a real number with 2 digits before and after the decimal point. So if you were printing a real number you'd use:

PRINT '(F5.2)', A

to get the rounded output.

In your example you're just printing text so there's no special formatting to do. Also if you leave the format specifier as * it will apply the default formatting to reals etc.

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