使用 g++ 包含来自不同文件夹的 header 文件

Question

I was trying to install FLTK library and saw header files that uses different directory. So I tried to test it out as:

\\check.cpp in D:\C++\
#include <factorial.h> // self made header file in folder D:\C++\link\
#include <iostream>
int main(){
\\ blah blah and call to factorial function from factorial.h
}

Do NOTE: link folder contains 1. string.exe(simple exe) 2. factorial.h.. I am trying to compile check.cpp from D:\C++\ using cygwin as:

g++ this.cpp -ID:\C++\link -o done.exe 

When there is only factorial.h in link folder(D:\C++\link), the compilation successfully completes and produce working executable. But when there is another file string.exe in the same directory, the g++ tries to take exe file as input... The exact compile error is as:

In file included from 

/usr/lib/gcc/x86_64-pc-cygwin/7.4.0/include/c++/bits/locale_classes.h:40:0,
                     from /usr/lib/gcc/x86_64-pc-cygwin/7.4.0/include/c++/bits/ios_base.h:41,
                     from /usr/lib/gcc/x86_64-pc-cygwin/7.4.0/include/c++/ios:42,
                     from /usr/lib/gcc/x86_64-pc-cygwin/7.4.0/include/c++/ostream:38,
                     from /usr/lib/gcc/x86_64-pc-cygwin/7.4.0/include/c++/iostream:39,
                     from check.cpp:2:
    D:\C++\link/string:1:3: error: stray ‘\220’ in program
     MZ□       □□  □       @                                   □   □ □ □!□L□!This program cannot be run in DOS mode.

       ^
    D:\C++\link/string:1:5: error: stray ‘\3’ in program
     MZ□       □□  □       @                                   □   □ □ □!□L□!This program cannot be run in DOS mode.
         ^
    D:\C++\link/string:1:9: error: stray ‘\4’ in program
     MZ□       □□  □       @                                   □   □ □ □!□L□!This program cannot be run in DOS mode. 

As far as I can guess, using -ID:\C++\link\ tried to take string.exe as input or something like that...

Answer 1

Have you tried using slashes instead of backslashes? / instead of \ ?

I think what you see is the compiler trying to include string.exe when calling #include <string> somewhere in <iostream> .

Also calling the folder 'link' is kind of confusing, 'include' would be a better name.

It looks like you are using MinGW - this may help you: MinGW include path howto

[Can't comment so as an answer.]