等价的C与Fortran名称列表 [英] C equivalent to Fortran namelist

问题描述

我习惯到Fortran中，我使用的读取顺序的namelist得到变量出文件。这使我有一个文件，它看起来像这样

I am used to Fortran in which I used the namelist sequential read in to get variables out of a file. This allows me to have a file which looks like this

&inputDataList
n = 1000.0 ! This is the first variable
m = 1e3 ! Second
l = -2 ! Last variable
/

在那里我可以命名被它的名字的变量，并分配一个值，以及事后的评论说出什么变量实际上是。加载由

where I can name the variable by it's name and assign a value as well as comment afterwards to state what the variable actually is. The loading is done extremely easy by

namelist /inputDataList/ n, m, l
open( 100, file = 'input.txt' )
read( unit = 100, nml = inputDataList )
close( 100 )

现在我的问题是，有没有任何C类似的事情？或者，我将不得不通过砍在'='等字符串做手工？

Now my question is, is there any similar thing in C? Or would I have to do it manually by chopping the string at the '=' and so on?

推荐答案

下面是一个简单的例子，可以让你读C.我用你在问题中提供的名称列表文件的Fortran名称列表， input.txt的。

Here is a simple example that will let you read Fortran namelists from C. I used the namelist file that you provided in the question, input.txt.

Fortran的子程序 nmlread_f.f90 （注意使用 ISO_C_BINDING ）

Fortran subroutine nmlread_f.f90 (notice the use of ISO_C_BINDING):

subroutine namelistRead(n,m,l) bind(c,name='namelistRead')

  use,intrinsic :: iso_c_binding,only:c_float,c_int
  implicit none

  real(kind=c_float), intent(inout) :: n
  real(kind=c_float), intent(inout) :: m
  integer(kind=c_int),intent(inout) :: l

  namelist /inputDataList/ n,m,l

  open(unit=100,file='input.txt',status='old')
  read(unit=100,nml=inputDataList)
  close(unit=100)

  write(*,*)'Fortran procedure has n,m,l:',n,m,l

endsubroutine namelistRead

C程序， nmlread_c.c ：

#include <stdio.h>

void namelistRead(float *n, float *m, int *l);

int main()
{
  float n;
  float m;
  int   l;

  n = 0;
  m = 0;
  l = 0;

  printf("%5.1f %5.1f %3d\n",n,m,l);

  namelistRead(&n,&m,&l);

  printf("%5.1f %5.1f %3d\n",n,m,l);   
}

另请注意， N ， M 和→需要为了通过引用传递他们Fortran例程声明为指针。

Also notice that n,m and l need to be declared as pointers in order to pass them by reference to the Fortran routine.

在我的系统与英特尔编译器套件（我的gcc和gfortran是岁，不问）的编译：

On my system I compile it with Intel suite of compilers (my gcc and gfortran are years old, don't ask):

ifort -c nmlread_f.f90
icc -c nmlread_c.c
icc nmlread_c.o nmlread_f.o /usr/local/intel/composerxe-2011.2.137/compiler/lib/intel64/libifcore.a

执行的a.out 产生预期的输出结果：

  0.0   0.0   0
 Fortran procedure has n,m,l:   1000.000       1000.000              -2
1000.0 1000.0  -2

您可以编辑上面的Fortran程序，使之更加普遍，例如从C程序指定名称列表的文件名和目录名。

You can edit the above Fortran procedure to make it more general, e.g. to specify namelist file name and list name from the C program.

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