Hi All,

I am new to C++ on linux enviroment and am trying to use the png++ library for a project. The problem i am facing is that that a simple program i write using png++ incudes does not work and shows me the following errors

AProg.o: In function png::info_base::info_base(png::io_base&, png_struct_def*):
AProg.cpp (.text._ZN3png9info_baseC2ERNS_7io_baseEP14png_struct_def[_ZN3png9info_baseC5ERNS_7io_baseEP14png_struct_def]+0x21): undefined reference to png_create_info_struct
AProg.o: In function png::info::write() const:
AProg.cpp:(.text._ZNK3png4info5writeEv[png::info::write() const]+0xd4): undefined reference to png_set_PLTE
AProg.cpp:(.text._ZNK3png4info5writeEv[png::info::write() const]+0x137): undefined reference to png_set_tRNS
AProg.cpp:(.text._ZNK3png4info5writeEv[png::info::write() const]+0x14f): undefined reference to png_write_info
AProg.o: In function png::info::sync_ihdr() const:
AProg.cpp:(.text._ZNK3png4info9sync_ihdrEv[png::info::sync_ihdr() const]+0x79): undefined reference to png_set_IHDR
AProg.o: In function png::end_info::destroy():
AProg.cpp:(.text._ZN3png8end_info7destroyEv[png::end_info::destroy()]+0x48): undefined reference to png_destroy_info_struct
AProg.o: In function png::end_info::write() const:
AProg.cpp:(.text._ZNK3png8end_info5writeEv[png::end_info::write() const]+0x1a): undefined reference to png_write_end
AProg.o: In function png::io_base::set_swap() const:
AProg.cpp:(.text._ZNK3png7io_base8set_swapEv[png::io_base::set_swap() const]+0x1b): undefined reference to png_set_swap
.............. (and it goes on).

The background of what i have done so far.

1 : I have gcc/g++ configured correctly.

2 : I have followed the following instructions ( http://www.techsww.com/tutorials/libraries/libpng/installation/installing_libpng_on_ubuntu_linux.php ) and correctly install libpng-1.2.50. The result seems to be correct.

This is how my usr/local folder looks now

:/usr/local/include$ ls
libpng12 libpng15 png++ pngconf.h png.h pnglibconf.h

:/usr/local/include$ ls
libpng12 libpng15 png++ pngconf.h png.h pnglibconf.h

:/usr/local/lib$ ls
libpng12.a libpng12.so libpng12.so.0.50.0 libpng15.la libpng15.so.15 libpng.a libpng.so libpng.so.3.50.0 python2.7
libpng12.la libpng12.so.0 libpng15.a libpng15.so libpng15.so.15.12.0 libpng.la libpng.so.3 pkgconfig

:/usr/local/bin$ ls
eclipse libpng-1.2.50 libpng12-config libpng-1.5.12 libpng15-config libpng-config png++-0.2.5

3 : After that i followed the following ( http://www.nongnu.org/pngpp/doc/0.2.5/ ) to install the png++-0.2.5 and all the five steps didnt gave any error.

But after that when i tried to compile a simple program (with the instructions given at the same site : http://www.nongnu.org/pngpp/doc/0.2.5/ ) it would not compile.

:~/workspace/AProg$ g++ -o AProg AProg.o 'libpng-config --ldflags'
g++: error: libpng-config --ldflags: No such file or directory

Then i tried to solve the problem and google it and gave this command which seems to work fine at compile but when i tried to run it. I got the error as mentioned at the top of the post

:~/workspace/AProg$ g++ -c AProg.cpp -I/usr/local/include/libpng12 -L/usr/local/lib -lpng -I/usr/local/include/png++


I am sorry for such a long post. But i just wanted to explain anything /everything related to my problem. Hope somebody helps me here.

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The program that you have written, is it correct ? Post your program.

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The program that you have written, is it correct ? Post your program.

Quotes in linker line, is not correct. It should be back quotes. The one in tilde button under escape button.

commented: Thanks, it worked +0
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