VSCode IntelliSense proposes a .h file but marks it not found - c++

Question

I can't compile a simple stupid demo "project" using visual Studio Code.
As I'm trying to enrich my knowledge portfolio, I trying to learn the basics manually, as to speak I try to compile code manually, without that the Visual Studio Enterprise IDE does all automatically. So I decided to use Visual Studio Code on Mac + clang++ for a simple demo project.
My problem is: I have a Workspace. In this workspace, I have some directories. One Of those directories called Functions and Headers contains again directories: debug, release, include, src. In the src directory, I have the functions.cpp file containing two dummy methods:
int add(int x, int y)
{
return x + y;
}
int subtract(int x, int y)
{
return x - y;
}
and in the main.cpp:
#include "functions.h"
int main()
{
int x = add(1, 3);
int y = subtract(5,1);
return 0;
}
In my include folder I have two method declarations:
int add(int x, int y);
int subtract(int x, int y);
The interesting point is: When I'm in main.cpp and I type #include " then IntelliSense finds the functions.h and proposes that file to me.
Also, the method calls are highlighted correctly. But: after including the file, Visual Studio Code marks the file read and says: functions.h file not found.
Is that a visual Studio Code bug? Because I also had a look on the settings and the settings seems ok (see picture).
Clang writes:
Ginos-MBP:src ginovalentinopensuni$ clang++ functions.cpp main.cpp main.cpp:2:10: fatal error: 'functions.h' file not found
#include "functions.h"
^~~~~~~~~~~~~ 1 error generated.
Do I miss something or am I doing something wrong? I also looked at the other similar questions here, but there was nothing helpful.
Pictures:

Answer 1

Indeed. The VSCode include path that allowed #include "functions.h" to be autocompleted has no bearing on what is a valid path to the compiler. There are two ways to address this:
Fix the path in the source file
Since you are including the header functions.h from the ./src directory, try instead writing:
#include "../include/functions.h"
int main()
{
int x = add(1, 3);
int y = subtract(5,1);
return 0;
}
This should work. Unless a specific include path is given to the compiler, clang++, like most other C++ compilers, will interpret the path relative to the location of the source file. In this case, it needs to go up a directory and then into the include directory in order to locate the functions.h header file.
Add an include path to that of clang++
From reading the clang++ man page, it can be ascertained that the -I flag may be used to specify an additional include path for the compiler to search to find header files. So, assuming that the command was run from the ./ directory, one jump out of the src directory and the root of the project:
clang++ src/main.cpp -I./include
would also address the issue at hand.