Fortran中的可分配字符变量 [英] Allocatable character variables in Fortran

问题描述

我的代码（分为我认为与此问题相关的）是

  PROGRAM测试
 
 IMPLICIT NONE 
 
 CHARACTER（len = 37）input 
 CHARACTER（len = :)，allocatable :: input_trim 
 
 
 WRITE ，*）'文件名？'
输入
 ALLOCATE（字符（len = LEN（TRIM（输入）））:: input_trim 
 
。 
。 
。 
 
 END PROGRAM测试
  

它适用于Intel的Fortran编译器，不过gfortran给我一些错误，第一个在行

  CHARACTER（len = :)，allocatable :: input_trim 
  

我不知道哪个编译器对于Fortran标准是正确的。加上我不知道如何实现我需要一个不同的方式？我想我做的更多是一个解决方法。我需要的是一个字符变量，其中包含的输入文件名没有下面的空格。

编辑：错误是CHARACTER声明中的语法错误。
gfortran --version给我GNU Fortran（GCC）4.4.7 20120313（Red Hat 4.4.7-3）

编辑2： re right关于分配：有了ifort，我不需要它。 gfortran崩溃之前，所以也许它不需要分配，但我不能测试这一刻...

解决方案

此

 字符（len = :)，allocatable :: input_trim 
  pre> 
 
 
当然在Fortran 2003中语法正确。你不说什么错误， gfortran 所以我不能评论为什么它不接受行 - 也许你有一个旧版本的编译器安装。
 
 
 
有了最新的Fortran编译器（例如 Intel Fortran v14.xxx）在分配字符变量之前不需要分配字符变量的大小，您只需写
  input_trim = trim（input）
  
 / p> 
 
 
 阅读（*，*）input_trim 
  
无效。
 
My code (stripped down to what I think is relevant for this question) is
PROGRAM test

IMPLICIT NONE

CHARACTER(len=37) input
CHARACTER(len=:), allocatable :: input_trim


WRITE(*,*) 'Filename?'
READ(*,*) input
ALLOCATE(character(len=LEN(TRIM(input))) :: input_trim)
input_trim=trim(input)

.
.
.

END PROGRAM test
It works fine with Intel's Fortran compiler, however gfortran gives me a couple of errors, the first one being in the line saying
CHARACTER(len=:), allocatable :: input_trim
I'm not sure which compiler is 'right' regarding the Fortran standard. Plus I don't know how to achieve what I need in a different way?! I think what I'm doing is more of a workaround anyway. What I need is a character variable containing exactly the filename that was entered with no following spaces.

EDIT: The error is "Syntax error in CHARACTER declaration".
gfortran --version gives me "GNU Fortran (GCC) 4.4.7 20120313 (Red Hat 4.4.7-3)"

EDIT 2: You're right regarding the allocate: With ifort, I don't need it. And gfortran crashes before that so maybe it doesn't need the allocate either but I cannot test this at the moment...
解决方案
This
character (len=:), allocatable :: input_trim
is certainly syntactically correct in Fortran 2003. You don't say what the error that gfortran raises is, so I can't comment on why it doesn't accept the line -- perhaps you have an old version of the compiler installed.

With an up-to-date Fortran compiler (eg Intel Fortran v14.xxx) you don't need to allocate the character variable's size prior to assigning to it, you can simply write
input_trim = trim(input)
Note that 
read(*,*) input_trim
won't work.

                        
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