"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!