undefined reference to a function

This is a discussion on undefined reference to a function within the C Programming forums, part of the General Programming Boards category; Hi, i need to work with images, so I downloaded GDLibrary. It is in one directory, in another one I ...

  1. #1
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    undefined reference to a function

    Hi,

    i need to work with images, so I downloaded GDLibrary.
    It is in one directory, in another one I have my .c file.

    In my .c file I import the library with a sentence like
    #include "../thaPath/gd.h"

    In my .c I saw that I have no problems using (declaring) types defined in gd.h,
    but when I try to use functiones defined there...I got the "undefined reference to..." error message.

    I am working under a Red Hat Linux 9 in case the information is worth....

    Thanks in advance for any suggestion...

  2. #2
    old man
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    It sounds like you're not linking in the library. If you're using gcc, look at the -l switch.

  3. #3
    Registered User
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    Thank you very much!
    At this moment I am at work so I cant try what you suggests, but it sounds very probable.

  4. #4
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    Unfortunately I still doesnt work...

    I tell you my situation.

    Installed GDLibrary package, running ./configure, than the make and after that the make install; as the INSTALL file says...

    Now I got my gd.h in /usr/local/include
    and my libgd.a and also my libgd.a, libgd.la, libgd.so in /usr/local/lib

    and I still got the
    undefined reference when I try
    gcc -Wall myFile.c -lgd

    Any suggestions???

  5. #5
    ex-DECcie
    Join Date
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    Quote Originally Posted by rodrigouy
    Unfortunately I still doesnt work...

    I tell you my situation.

    Installed GDLibrary package, running ./configure, than the make and after that the make install; as the INSTALL file says...

    Now I got my gd.h in /usr/local/include
    and my libgd.a and also my libgd.a, libgd.la, libgd.so in /usr/local/lib

    and I still got the
    undefined reference when I try
    gcc -Wall myFile.c -lgd

    Any suggestions???

    This is what I do -- your mileage may vary. I'm assuming that you're on Linux, based on your "/usr/local/lib"

    In /etc there is a file called /etc/ld.so.conf. In there you can specify locations where shareable libraries are located on your machine. If /usr/local/lib is not in there, put it in there and run ldconfig. (You might need to be root to do that).

    Then, I'd compile like:

    gcc -Wall -lgd myFile.c

    Or, to make sure that nothing else is amiss first, before all that, you could try:

    gcc -Wall -L/usr/local/lib -lgd myFile.c


    Try looking at man ldconfig, man ld.so and man ld for more information.

  6. #6
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    Thank you very much!
    As you said /usr/local/bin wasnt in ld.so.conf file...

    after adding that line and running ldconfig most of my
    undefined references dissapeard,
    all but one, that keeps there...

    I really got no clue whats happening...

  7. #7
    old man
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  8. #8
    Registered User
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    Thanks a lot, it seems i was in hurry to program...

    I hope after reading what you linked carefully (and obviusly after dealing with new problems) I can start to use GDLibrary.

    Thanks a lot again!

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