I'm trying to write a program using flex++, however everytime I try to compile I receive the error message:
FlexLexer.h: No such file or directory
However that header is found on the include folder of flex. I don't have problems compiling lex programs for c, however for c++ with flex++ I can't seem to find a way.
I already downloaded flex various times and I don't know if there is a problem with my OS or something like that. My OS is Windows 10.
Thank you
Including should be pretty straightforward once you understand how it works.
Let's look at some different ways you can include a file:
#include "FlexLexer.h"
The quotes tell the compiler to look for the file FlexLexer.h in the same folder as the file being compiled. That is it, it won't look anywhere else.
Now if we change the quotes to brackets:
#include <FlexLexer.h>
This tells the compiler to look for FlexLexer.h in the same folder first, but then if it isn't found it will go through the list of include paths looking for it there, too.
Assuming you are using VisualStudio, there is both a system list of include paths (see Tools > Options > Projects and Solutions > VC++ Directories) and a project list of include paths (right click on the Project in the Solution Explorer, Properties > VC++ Directories). Both of these lists are traversed.
Finally, you can also add subdirectory qualifies to the include, e.g.:
#include "Win\FlexLexer.h"
or
#include <Win\FlexLexer.h>
As you might guess, it looks for the path under either the current directory in the both examples and also under the include path list in the later example. Regardless, the first time the file is found the search will stop and the compiler will use it. So be careful if there are headers will duplicate names in different libraries!
Related
I was trying to re-use an available source code for my own project, it can be found here:
https://github.com/TadasBaltrusaitis/OpenFace
I tried compiling project FeatureExtraction of the original code, everything was fine. Then I created a new empty project and added the following #include:
#include "LandmarkCoreIncludes.h"
#include <Face_utils.h>
#include <FaceAnalyser.h>
#include <GazeEstimation.h>
These are exactly the same as in project FeatureExtraction in the provided source code. I've already changed the additional include directories in C/C++ general tab into:
$(SolutionDir)\lib\local\FaceAnalyser\include
$(SolutionDir)\lib\local\LandmarkDetector\include
However, it still gave me "cannot open source file error".
Update: If I put the absolute path of the header file directly to the code it is OK, however if I put the absolute path to the Additional Include Directories, the error remained.
Use #include "header.h" instead of the one with diamonds (< and >) which looks in another directory.
After that, check if the header files really are in these directories. If they are, you should check the $(SolutionDir) ( I don't use a '\' after the $(SolutionDir) but it may work out as well).
Try to locate and delete the .suo file and restart VS
Looks like I had same "bug" as mentioned in this post here:
Visual Studio does not honor include directories
After having changed the Additional Include Directories for all platforms instead, the code was compiled without any errors.
There are already many options listed of how to add a path to a C++ compiler so that the #include <...> command works on these paths. However, assume that I have a single file (not an entire project) and I want to add an include path just for this file alone. I'd like to do this via a line of code within the cpp-file (say, as very first line). How is this possible? Why? Because I need to include some header file from another directory which in turn depends also on other header files within that same directory (and I get error messages that these other files could not be found due to the fact that this path was not added to the include-list).
For example:
Let's assume I want to include file_a.h in directory
.../include/extra,
I can do that via
#include <extra/file_a.h>
However, if, e.g., I do not have the extra-directory directly as a sub-directory of include, or the file_a wants to include some other file from somewhere else (maybe even /extra, but it's not a sub directory of include e.g.), then I run into trouble, because then the tracking of directories/dependencies gets hard.
I thought it would be a bad habit to change those directories via compiler, so I thought better solution would be to integrate it into the program, so no matter which compiler I use, it would work anyway without even having to think about afterwards, once specified, which directories I have to add.
Per my understanding you did:
#include <absolute/path/to/header/header.h
or
#include <relative/path/to/header/header.h
But into the header.h some other include are included.
#include <header_1.h>
#include <header_2.h>
[...]
#include <header_n.h>
Those other headers haven't relative/absolute path, so compiler doesn't know how to find them.
To solve this you can use (using gcc) the -I compiler option:
-I dir
Add the directory dir to the list of directories to be searched for header files during preprocessing. [...]
Emphasis mine
So you can use
#include <header.h>
In your file and compile it using
gcc ... -I/path/to/headers ...
When you have to specify one or more include paths in the compile command, you can do it as follows:
g++ -I/path1/to/headers -I/path2/to/headers YourProgram.cpp
Include paths tell the compiler where it finds the files it actually shall include into other files. This is (usually) controlled via compiler options as LPs explained in this answer.
C++ standard does not provide any facilities to do this from within a C++ source file and I am not aware either of any compiler extension of any vendor that would allow doing so, so bad luck...
Now depending on the IDE you are using (hopefully you are using one...), though, you most likely can add include paths for files individually there (would be a strange IDE if it didn't allow...), e. g. with eclipse + GCC, right click the file, select "Properties" -> C/C++ Build -> Tool Settings -> GCC C++ Compiler -> Includes.
Alternatively you could use a make file instead (actually, eclipse in standard settings generates one for you automatically...), which again allows you to set compiler options for each file individually - either written directly by yourself or generated by some other tools facilitating this such as cmake.
So a few hours ago I started learning c++ in codelite but I was getting frustated with, so I just got codeblocks and imported the project. But now whenever I try to compile it returns:
fatal error: imports.h: No such file or directory
This is my project hierarchy in codeblocks:
And this is what the project folder looks like:
What am I doing wrong?
I know this is years later, but I've recently seen students following what I deem is frankly bad advice such as what is given above. For those learning c++ this functionality is NOT for you. To add headers you should simply check that you are using double quotes, instead of angled brackets i.e.
#include "myheader.h"
and NOT
#include <myheader.h>
Angled brackets are meant for libraries (informally) and adding a simple header file for you basic classes does not require you to change default search directories. The problem comes when someone else tries to run your code (assuming you're doing this for uni) and their IDE isn't setup to search for a "library" (your header) where it shouldn't be. Double quotes tells the compiler the files exist in your current relative directory. This way you can keep your main, headers and header implementation in one directory. Fiddling with your IDE should only be done when necessary. KISS
You have to tell Codeblocks where to find the header files that you include. Try adding the full path to your '/Headers' in the include directories of codeblocks
Goto 'Codeblocks menu > Settings > Compiler > Search directories > Add'.
EDIT: Since your issue, however, is quite irrelevant to learning the C++ language itself, I suggest that you start with simpler programs, then move on to more complex ones. That, of course, unless you have previous experience with other programming languages
Since I haven't found any Makro for
#define 'hostname of device where compiler is located' // which is unique and not to be copied !
I have now successfully used and included
#include "myCompileEnv.h"
as a workaround with the comments above, which is located more central - above the project directories in CodeBlocks.
I want to include a header file. I am working in a C++ environment, (C++11, Windows OS, Netbeans 7.3.1 IDE, Cygwin_4.x tool collection). I do not know how I setup the environment/IDE (I did it 6 months ago). I do not understand the fundamentals of the C++ build process or Cygwin related issues either, so I might have to fill in the gaps with some other references/documentation (on what specifically, I'm not sure).
My ultimate objective is to be able to include header files using a syntax that does not require the full file path. I want to write something terse, like:
#include "src\stuff\blah.h" //or even better: #include "blah.h"
The only way I can get my program to compile at all is by using the full file path, like this:
#include "C:\NetBeansProjects\Project1\src\stuff\blah.h"
And, I can only compile once using the full path. If I try to rebuild, it will bomb with the *** multiple target patterns. Stop. error. There are workarounds for this error; those being either 1) deleting the build and dist folders between each rebuild (yikes?), or 2) following this 16 step setup process.
I do not want to follow either of those workarounds because they do not appear to deliver what I want. How can I setup my environment to achieve what I want...of being able to include header files without using full paths?
Thanks to DanielKO for this answer.
In my case, I was able to include with the syntax:
#include "../stuff/blah.h"
I did not have to configure anything under the "Code Assistance" section for the C++ compiler.
All of my code is under "src" as the parent directory in my NetBeans project. It seems that the full path of the file is not required, and the only directory that must be referenced is the lowest level subdirectory (in my case, "stuff").
In NetBeans I've added the path to the list of libraries:
Go to Properties->Select C++->Select 'include libraries'->'Add'
Now: Add the path of the project folder with option "absolute"
Go to Properties->Select C++->Select 'Additional library directories'->'Add'
Now: Add the path of the project folder with option "absolute"
It's very obscure to me why the project doesn't recognize "own" header files.
I'm trying to get Xcode to import the header file for Irrlicht.
#include <irrlicht.h>
It says "Irrlicht.h. No such file or directory". Yes Irrlicht.h with a capital I, even though the #include is lowercase.
Anyway I added "/lib/irrlicht-1.6/include" in the header search paths for the Xcode project, yet it still doesn't find it.
The only thing I've tried that does work is:
#include "/lib/irrlicht-1.6/include/irrlicht.h"
This is a bit ridiculous though, #include should work, I don't understand why it isn't working.
Update (here are more details on the error):
/lib/PAL/pal_benchmark/palBenchmark/main.h:31:0
/lib/PAL/pal_benchmark/palBenchmark/main.h:31:22: error: irrlicht.h: No such file or directory
I figured this out. Perhaps someone can comment as to why this is the case.
The Header was located in this directory:
/lib/irrlicht-1.6/include/
If I added that path to: "Header Search Paths" Xcode still wouldn't find the path when I built the project.
Solution: Add the header path to: "User Header Search Paths" instead.
It boggles me why I had to do this, as I frequently add my header paths to "Header Search Paths" and then #includes just work. Hopefully this can help someone else who gets this same issue.
Both
#include <irrlicht.h>
#include "irrlicht.h"
should work as long as the "-I" argument to gcc includes the path of the directory enclosing the header file. If irrlicht.h is part of /usr/include the "-I" option is no longer required.
Rather than explicitly adding include paths to your project settings, an easier and more convenient solution for this kind of situation is to just drag the directory containing your .h files (/lib/irrlicht-1.6/include in this case) into the project files pane. This adds the headers to your project of course, and makes it easy to browse them and search for symbols, etc, and it also adds the directory path to gcc compiles, so that you don't have to manage include paths explicitly.
and furthermore, a flat file hierarchy isn't what you want. Dragging files into Xcode flattens your hierarchy. What about for example when you want to have multiple Targets, with a "TargetName/settings.h" file for that target. you'll have many settings.h files that you need to keep unique via its folder name.
I understand that this is an old post, but it does rank quite high on Google, so I thought I would add some information
Under XCode 3.2.6, I had an issue where XCode could not find a header file. It turns out that one of the filepaths included a space in it, and XCode interpreted it improperly.
For example: With a path like "Users/Username/Desktop/Project/Some Headers"
Here was the excerpt from the GCC Commandline: "-I/Users/Username/Desktop/Project/Some" "-I/Headers"
To see your build log provided by XCode, there is a good tutorial here: How do you show Xcode's build log? (Trying to verify if iPhone distribution build zip was created correctly.)