INCLUDEPATH in qmake project file doesn't work

Question

I've got a problem with include in a qmake project. In my .pro file I've got:

INCLUDEPATH += "C:\OpenCV\build\include"

and in my cpp :

#include <opencv\cv.h>

The compiler indicates an error:

Cannot open include file: 'opencv\cv.h': No such file or directory

but if I write this in my cpp:

#include "C:\OpenCV\build\include\opencv\cv.h"

it works!

I build the project from within Qt Creator. What am I doing wrong?

Did you try to set `INCLUDEPATH += "C:\\OpenCV\\build\\include"` and use `#include ` in your source file? — vahancho, Sep 27 '13 at 10:10
OK I found the solution here : http://stackoverflow.com/questions/14742856/qt-creator-adding-external-library-still-cannot-open-include-file-gl-glew-h I had the rerun qmake -.-' — user2794529, Sep 27 '13 at 10:54
This question just saved my bacon: INCLUDEPATH += "C:\some\dir" in .pro, #include , delete build- directory, qmake, and rebuild project. — , Jul 19 '17 at 12:22

score 17 · Answer 1 · answered Dec 24 '14 at 13:40

17

You have to run qmake(build->run qmake) to validate changes in the pro file. Qt creator Adding external library (still: Cannot open include file: 'GL/glew.h')

answered Dec 24 '14 at 13:40

Flu2fy Unicorn

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Small tip: Qt cannot recognize spaces in path. – Summer Sun Sep 18 '17 at 13:35

score 9 · Answer 2 · edited May 23 '17 at 12:09

9

Your problem may be related to the fact that having backslashes in naked #include directives is undefined behavior.

Do the following.

Replace your include with
```
#include <opencv/cv.h>
```
Note the forward slash!
Remove the shadow build directory that Qt Creator has made for you. You will find it above the project directory, its name begins with build-.
Rebuild the project.

Note that this takes care of rerunning qmake.

edited May 23 '17 at 12:09

Community

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answered Sep 27 '13 at 13:22

Kuba hasn't forgotten Monica

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I can add that backslashes should be replaced to forward slashes in INCLUDEPATH content too. – NordMan Nov 10 '22 at 13:22

score 3 · Answer 3 · answered Sep 27 '13 at 10:10

here's one of my pro files:

    # Blah Application

TEMPLATE  = app
CONFIG   += qt console staticlib debug_and_release
QT       -= gui
QT       += network sql xml
TARGET    = blah

CONFIG(debug, debug|release){
    DESTDIR = debug
    LIBS += -L../../../lib/core/debug -lcore
} else {
    DESTDIR = release
    LIBS += -L../../../lib/core/release -lcore
}
DEPENDPATH  += . ../../lib ../../../lib/core
INCLUDEPATH += . ../../lib ../../../lib/core

# Library files
HEADERS += mtBlahRTP.h
SOURCES += mtBlahRTP.cpp

# Input
HEADERS +=
SOURCES += main.cpp

The include path points to the RELATIVE directory of my lib files. mtBlahRTP.h and mtBlahRTP.cpp are in ../../lib

score 3 · Answer 4 · edited Jan 20 '17 at 17:21

3

I have the same question, before building or running, you should qmake(Build=>qmake) it.

My configurations for INCLUDEPATH:

INCLUDEPATH+=D:\opencv\opencv\build\include
INCLUDEPATH+=D:\opencv\opencv\build\include\opencv
INCLUDEPATH+=D:\opencv\opencv\build\include\opencv2

edited Jan 20 '17 at 17:21

pringi

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answered Jan 20 '17 at 13:48

user7446574

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When using multiple line `INCLUDEPATH`'s, make sure you use `+=` (not `=`) - as I just found out to my cost – Anonymouse Feb 25 '19 at 10:56

score 1 · Answer 5 · answered Aug 27 '15 at 20:41

I ran into a similar issue and what I found is that the QtCreator IDE is not re-reading the results of qmake and updating the "Cannot open" message. You need to close the offending file and re-open it - then you'll see that it no longer displays the error.

score 1 · Answer 6 · answered Feb 19 '16 at 12:11

1

I had to do two steps: (re-)run qmake and rebuild the whole project - only then the INCLUDEPATH setting was considered correctly. (With QtCreator 3.5 and 3.6 (Qt 5.5 and Qt 5.6) on Windows.)

answered Feb 19 '16 at 12:11

Dynamo72

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score 1 · Answer 7 · answered Aug 19 '18 at 06:24

The only problem you are making is incorrectly linking the OpenCV library. The other answers given here may or may not work, but I have posted on another thread a surefire way to solve this problem using the "Add Library" wizard inside Qt Creator: https://stackoverflow.com/a/51914928/10245006

score 0 · Answer 8 · edited Jun 10 '16 at 10:23

I was getting the error:

canserialcomm.o: In function `CanSerialComm::CanSerialComm()':
canserialcomm.cpp:(.text+0xc1): undefined reference to `vtable for CanSerialComm'

It turns out that the cause was it wasn't able to find canserialcomm.h where that constructor is declared. This was despite me having INCLUDEPATH in the project file point to the directory containing that header file:

INCLUDEPATH += . \
        ..

What I had to do to fix this is explicitely specify the header file; I added:

HEADER += ../canserialcomm.h

Raiden Core · Answer 9 · 2016-06-15T10:10:22.997

0

You should use double backslashes when in windows for qt creator with msvc. like this: INCLUDEPATH += C:\\libcurl\\libcurl-vc-x64-release-dll-ipv6-sspi-winssl\\include

this will fix the problem.

edited Jun 15 '16 at 10:10

answered Jun 15 '16 at 08:28

Raiden Core

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score 0 · Answer 10 · answered Aug 30 '16 at 15:28

Under windows you have to eliminate the -I before each directory that is added into the INCLUDEPATH variable. For example: Under windows:

INCLUDEPATH += "C:\lib\boost_1_61_0" (back-slash)

Under linux & mac:

INCLUDEPATH += -I"$$(HOME)/lib/boost_1_61_0" (note the -I and forward-slash)

I'm not sure whether it depends on different qmake version or not. But after finishing qmake command, I check the Makefile and the double -I is the issue.

score 0 · Answer 11 · answered Jan 12 '17 at 13:48

You need to do several things. Fist, in the .pro file, you need quotation marks two backslashes at a time, like this:

INCLUDEPATH += "C:\\OpenCV\\build\\include\\opencv\\cv.h"

You alse need a frontslash in the #include in your .cpp file like this:

#include <opencv/cv.h>

When you've done this, delete the build folder. This is the folder with a very complicated name of the type build-untitled-Desktop_Qt_5_7_0_MSVC2015_32bit-Release. Then, in the Build menu, press "Run qmake". When you've done all this, it should compile fine.

score 0 · Answer 12 · answered Aug 07 '18 at 12:09

0

Somehow it did not work for when I had several INCLUDEPATH +=. When I combined the stuff into a single on it suddenly worked.

answered Aug 07 '18 at 12:09

Slava

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INCLUDEPATH in qmake project file doesn't work

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