openCV error : undefined reference to `cvLoadImage' Ubuntu

Question

I have installed the openCV libraries but I am still getting the error
$ g++ -I /usr/include/opencv/ -L -lcxcore -lhighgui hello.cpp -o hello
/tmp/ccjjrbXr.o: In function main': hello.cpp:(.text+0x2d): undefined reference tocvLoadImage'
collect2: ld returned 1 exit status

When I check for the path of the libraries I get
$ pkg-config --libs opencv
-lml -lcvaux -lhighgui -lcv -lcxcore

I have written a very simple program to test it :

enter code here

#include< cv.h>  
#include< highgui.h> /* required to use OpenCV's highgui */
#include< stdio.h>

int main() { 
    IplImage* img = 0;
    printf("Hello\n");
    img = cvLoadImage("lena.jpg", 0 );
}

There is something wrong with my installation but I am really not able to figure it out. Any guidance will be highly appreciated! Thanks

---

When I run:

$ pkg-config --cflags --libs opencv
-I/usr/local/include/opencv -I/usr/local/include
/usr/local/lib/libopencv_calib3d.so /usr/local/lib/libopencv_contrib.so 
/usr/local/lib/libopencv_core.so /usr/local/lib/libopencv_features2d.so 
/usr/local/lib/libopencv_flann.so /usr/local/lib/libopencv_gpu.so 
/usr/local/lib/libopencv_highgui.so /usr/local/lib/libopencv_imgproc.so 
/usr/local/lib/libopencv_legacy.so /usr/local/lib/libopencv_ml.so 
/usr/local/lib/libopencv_nonfree.so /usr/local/lib/libopencv_objdetect.so 
/usr/local/lib/libopencv_photo.so /usr/local/lib/libopencv_stitching.so 
/usr/local/lib/libopencv_ts.so /usr/local/lib/libopencv_video.so 
/usr/local/lib/libopencv_videostab.so  

But when I run:

$ g++ 'pkg-config --cflags --libs opencv' display_image.cpp
g++: error: pkg-config --cflags --libs opencv: No such file or directory

OpenCV seems to be installed but still the problem persists.

Solution

You used single quotes ' instead of backquotes/backticks `. This is the corrected command:

g++ hello.cpp -o hello `pkg-config --cflags --libs opencv` 

Comments

[Admin]

Sorry, I actually had entered linked all the libs, but made a mistake while entering it the forum. It still gives the same error: '** g++ -I /usr/include/opencv/ -L -lhighgui hello.cpp -o hello /tmp/ccw90mKu.o: In function main': hello.cpp:(.text+0x2d): undefined reference to cvLoadImage' collect2: ld returned 1 exit status '**

[Martin Beckett]

@user1111044 - then it probably can't find the lib. Don't you have to specify a directory if you use "-L" ? this might be blocking the standard LD_LIBRARY_PATH search

[Admin]

Yeah that's the exact problem that I am facing. I do not have a folder to use along with the -L.

[Martin Beckett]

It's probably /usr/local/lib but see opencv.willowgarage.com/wiki/InstallGuide_Linux

[Admin]

nah..have tried all these. But thanks a lot Martin for trying to help!