问题描述
我最近正在处理F90代码项目.我使用gfortran(Linux和MinGW的)进行编译.文件loct.F90中有一些有趣的东西.
I am recently working with a F90 code project. I am using gfortran (linux and MinGW) to compile it. There is something interesting in file loct.F90.
# define TYPE real(4)
# define SUBNAME(x) s ## x
# include "loct_inc.F90"
# undef SUBNAME
# undef TYPE
# define TYPE real(8)
# define SUBNAME(x) d ## x
# include "loct_inc.F90"
# undef SUBNAME
# undef TYPE
...
在loct_inc.F90文件看起来像这样:
The loct_inc.F90 file looks like this:
subroutine SUBNAME(loct_pointer_copy_1)(o, i)
...
end subroutine SUBNAME(loct_pointer_copy_1)
subroutine SUBNAME(loct_pointer_copy_2)(o, i)
...
end subroutine SUBNAME(loct_pointer_copy_2)
...
我认为该文件中loct.F90作者使用套宏指令(C/C ++样式).每一组用于定义数据类型(例如，实数(4)，实(8)，字符等).文件loct_inc.F90提供了一组函数，除了变量的类型外，其余函数相同.这两个文件一起工作，如C ++在我看来的模板.
I think in the file loct.F90 the author used sets of macros (C/C++ style). Each set is used to define a data type (e.g. real(4), real(8), character, etc). The file loct_inc.F90 provide a set of function which is the same except the type of the variables.These two files works together as a template of c++ in my opinion.
在结束一个应当具有一组子程序:
In the end one should have a set of subroutines:
sloct_pointer_copy_1(o, i)
sloct_pointer_copy_2(o, i)
...
dloct_pointer_copy_1(o, i)
dloct_pointer_copy_2(o, i)
...
但是，当我试图编译loct.F90(gfortran -c loct.F90)，我得到了一些错误.
But when I tried to compile loct.F90 (gfortran -c loct.F90), I get some errors.
子例程s ## loct_pointer_copy_1(o，i) 1个错误:语法错误在SUBROUTINE语句在(1)
subroutine s ## loct_pointer_copy_1(o, i) 1 Error: Syntax error in SUBROUTINE statement at (1)
似乎gfortran用s ## loct_pointer_copy_1(o，i)替换了SUBNAME(loct_pointer_copy_1)(o，i).但是根据c ++宏，正确的替换应该是sloct_pointer_copy_1(o，i).
It seems gfortran replace SUBNAME(loct_pointer_copy_1)(o, i) with s ## loct_pointer_copy_1(o, i). But according to c++ macro, the correct replace should be sloct_pointer_copy_1(o, i).
谁能告诉我为什么会这样吗?
Could anyone tell me why this happened?
推荐答案
GNU Fortran在传统模式下使用GNU C预处理器，在该模式下，宏粘贴运算符##不可用.这就是为什么它被写入也与GNU的Fortran编译工具链的项目中额外的Makefile目标进行明确的预处理，例如所有是第一预处理的与临时档，然后编译.
GNU Fortran uses the GNU C Preprocessor in traditional mode, in which mode the macro pasting operator ## is not available. That's why Fortran projects which were written to also compile with the GNU toolchain perform explicit preprocessing in additional Makefile targets, e.g. all *.F90 are first preprocessed with cpp to temporary .f90 files which are then compiled.
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