"No rule to make target" error, when adding an external library to Qt Widget project.

tabakerkaaaa

Hello, i have a problem with adding an external library, called "libpng". I tried to change *.pro in different ways. First of all i tried adding those lines of code:

INCLUDEPATH += $usr/local/libpng/include
LIBS += -L$usr/local/libpng/lib -lpng

This is a default folder of libraries. It didn't work. After i downloaded all the files of "libpng" library manually and added those lines of code:

INCLUDEPATH += $usr/Qt/bin/headers
LIBS += $usr/Qt/bin/lib/libpng.lib -lpng

But there still was an error like this:
'png.h' file not found
#include "png.h"

Later i found out that i can add an external library via Qt Creator menu. I did it, so now i have this error:

:-1: Error: No rule to make target /Users/nikitababenko/CProjects/coursework2/bin/lib/liblibpng.a', needed by coursework2.app/Contents/MacOS/coursework2'. Stop.

Can anyone help me? Thanks everyone in advance. If you would need anything else from me, i would be glad to assist.

Christian Ehrlicher

@tabakerkaaaa said in "No rule to make target" error, when adding an external library to Qt Widget project.:

$usr

really $usr and not /usr? What OS are you using?

tabakerkaaaa

@Christian-Ehrlicher I use Mac OS and don't really know which one is correct. Found this solution somewhere on stackoverflow.

SGaist

Hi and welcome to devnet,

Where exactly are these files located on your system ?

tabakerkaaaa

@SGaist Hello, files, which were downloaded manually are located in /Qt/bin/
libpng, which was downloaded via cmd, is located in /usr/local/lib

SGaist

Then that's the path you should be using: -L/usr/local/lib or the subdirectory matching where the library is located.

tabakerkaaaa

@SGaist Wow, i feel so dumb now, i spend the whole day trying to connect it, and the solution is so simple. Thank you very much!