Trying to build C++ Dlib example fails to link with hundreds of undefined reference errors

Question

I'm trying to compile a DLIB example: http://dlib.net/image_ex.cpp.html and I copied it word-for-word:

#include <dlib/gui_widgets.h>
#include <dlib/image_io.h>
#include <dlib/image_transforms.h>
#include <fstream>


using namespace std;
using namespace dlib;

//  ----------------------------------------------------------------------------

int main(int argc, char** argv)
{
    try
    {
        // make sure the user entered an argument to this program
        if (argc != 2)
        {
            cout << "error, you have to enter a BMP file as an argument to this program" << endl;
            return 1;
        }

And I used this command:

g++ dlib1.cpp -o dlib1 -std=c++11 -O3 -I ~/Packages/dlib/ -lpthread -lX11 -ljpeg -lpng -DDLIB_JPEG_SUPPORT -DDLIB_PNG_SUPPORT

And despite that command working fine months ago: [Can't include the JPEG_SUPPORT headers in a dlib cpp file ] this time, it gave me hundreds of errors:

dlibTest-0.cpp:(.text._ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_[_ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_]+0x7e): undefined reference to `dlib::png_loader::is_gray() const'
dlibTest-0.cpp:(.text._ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_[_ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_]+0x94): undefined reference to `dlib::png_loader::is_gray() const'
dlibTest-0.cpp:(.text._ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_[_ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_]+0xaa): undefined reference to `dlib::png_loader::is_graya() const'
dlibTest-0.cpp:(.text._ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_[_ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_]+0xd0): undefined reference to `dlib::png_loader::get_row(unsigned int) const'
dlibTest-0.cpp:(.text._ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_[_ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_]+0x176): undefined reference to `dlib::png_loader::get_row(unsigned int) const'
dlibTest-0.cpp:(.text._ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_[_ZNK4dlib10png_loader9get_imageINS_7array2dINS_9rgb_pixelENS_33memory_manager_stateless_kernel_1IcEEEEEEvRT_]+0x1ce): undefined reference to `dlib::png_loader::is_graya() const'

What exactly is going wrong here?

Answer 1

Some of the samples need a command line such as ...

g++ -std=c++11 -O3 -I.. ../dlib/all/source.cpp -lpthread -lX11 example_program_name.cpp

I guess source.cpp is a "library as cpp code" link : dlib compile