问题描述
我有一个 Fortran 模块文件(filename.F)，其中包含一行语句:
I had a Fortran module file (filename.F), which contains a line of statement:
#include "module_io_domain_defs.inc"
我不太明白.为什么是#"符号.不应该只是
which I don't quite understand. Why is a "#" symbol. Should not be just
include "module_io_domain_defs.inc"
我知道在编译过程中，*.F 文件变成了*.f90 文件.如何理解上面的语句以及编译过程是如何工作的?
I know during the compilation process, the *.F file becomes *.f90 file. How to understand the above statement and how dose the compilation process work?
推荐答案
# 指定一个 C 预处理器指令.因此，#include 不是由 Fortran 编译器处理，而是由 C 预处理器(cpp、c-preprocessor).大写的 .F 而不是 f 通常告诉编译器在编译之前运行 cpp.
The # designates a C preprocessor directive. Therefore the #include is not processed by the Fortran compiler but by a C preprocessr (cpp, c-preprocessor). The capital .F instead of f typically tells the compiler to run cpp before compiling.
主要区别在于 #include 包含的文件将再次由 cpp 处理，而仅由 include 包含的文件将在编译之前不被任何东西处理.
The main difference is that the file included by #include will again be processed by cpp, whereas a file included just by include will not be processed by anything before compiling.
如果编译器无法识别大写F，也可以通过传递-cpp或-fpp等标志来请求预处理器在后缀中.
The preprocessor can also be requested by passing a flag such as -cpp or -fpp if the compiler does not recognize the capital F in the suffix.
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