如何使用隐式DO循环调试Fortran READ / WRITE语句？ [英] How can I debug a Fortran READ/WRITE statement with an implicit DO loop?

问题描述

 在文件的第182行。 ./SOURCE_FILE.f90（unit = 1，file ='INPUT_FILE.1'）
 Fortran运行时错误：在整数读取期间出现错误值
  

展望182行，我看到一条带有隐含/隐含DO循环的READ语句：

  182：READ（IT4,310）（（IPPRM2（IP，I），IP = 1，NP），I = 1,16）！读取6个整数
 183：READ（IT4,320）（（PPARM2（IP，I），IP = 1，NP），I = 1,14）！阅读5个reals 
  

格式声明：

  310 FORMAT（1X，6I12）
  

在调试器中 NP 的值为2. I 的值为6， IP 的值为67.我认为 I 和 IP 应该重新初始化循环。

我的问题是，当我尝试在调试器中逐步完成READ语句时，它似乎执行并抛出错误。我不确定如何按照它读取。我尝试着进入这个功能，但是由于我不熟悉gfortran库，似乎这可能是一条困难的路线。输入文件看起来不错，我认为它应该被读取得很好。这使得我认为这个READ语句没有像预期的那样循环。

我对Fortran和这种隐式DO循环完全陌生，但从我可以收集的第182行应根据格式字符串＃310读取6个整数。但是，当我到达时，NP 的值为2，这让我认为它只会尝试读取16次2个整数。

如何调试此读取语句，以检查从文件中读取的读入 IPPARM 的值？我将不得不逐步通过Fortran库？

任何提示可以消除我对这些隐式循环的困惑，我们将不胜感激！

谢谢！

注意：我在Linux上使用gfortran / gcc和gdb。

解决方案

变量IP和I是循环索引，因此它们由循环重新初始化。在NP = 2的情况下，第一个语句将读取总共32个整数 - 它有助于确定要读取的项目列表。格式决定了他们如何阅读。使用1X，6I12，它们将被读取为输入文件的每行6个整数。当所请求的32个整数中的前6个从行/记录读取时，Fortran将认为该行/记录已完成并前进到下一个记录。

1X，6I12整数必须精确排列在文件中。应该有一个空白，然后整数应该在12列的字段中右对齐。如果它们失去对齐性，可能会读取错误的值或运行时错误。

The Fortran program I am working is encountering a runtime error when processing an input file.

At line 182 of file ../SOURCE_FILE.f90 (unit = 1, file = 'INPUT_FILE.1')
Fortran runtime error: Bad value during integer read

Looking to line 182 I see a READ statement with an implicit/implied DO loop:

182:    READ(IT4, 310 )((IPPRM2(IP,I),IP=1,NP),I=1,16)    ! read 6 integers
183:    READ(IT4, 320 )((PPARM2(IP,I),IP=1,NP),I=1,14)    ! read 5 reals

Format statement:

310 FORMAT(1X,6I12)

When I reach this code in the debugger NP has a value of 2. I has a value of 6, and IP has a value of 67. I think I and IP should be reinitialized in the loop.

My problem is that when I try to step through in the debugger once I get to the READ statement it seems to execute and then throw the error. I'm not sure how to follow it as it reads. I tried stepping into the function, but it seems like that may be a difficult route to take since I am unfamiliar with the gfortran library. The input file looks OK, I think it should be read just fine. This makes me think this READ statement isn't looping as intended.

I am completely new to Fortran and implicit DO loops like this, but from what I can gather line 182 should read in 6 integers according to the format string #310. However, when I arrive NP has a value of 2 which makes me think it will only try to read 2 integers 16 times.

How can I debug this read statement to examine the values read into IPPARM as they are read from the file? Will I have to step through the Fortran library?

Any tips that can clear up my confusion regarding these implicit loops would be appreciated!

Thanks!

NOTE: I'm using gfortran/gcc and gdb on Linux.

解决方案

The variables IP and I are loop indices and so they are reinitialized by the loop. With NP=2 the first statement is going to read a total of 32 integers -- it is contributing to the determination the list of items to read. The format determines how they are read. With "1X,6I12" they will be read as 6 integers per line of the input file. When the first 6 of the requested 32 integers is read fron a line/record, Fortran will consider that line/record completed and advance to the next record.

With a format of "1X,6I12" the integers must be precisely arranged in the file. There should be a single blank, then the integers should each be right-justified in fields of 12 columns. If they get out of alignment you could get the wrong value read or a runtime error.

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