Problems with fink installed libpng at runtime

Posts: 22
Joined: 2006.04
Post: #1
I am attempting to use the libpng library that I installed using fink into /sw (as it seems to do by default). Being pretty new to all this stuff, - I've not tried using a library like this before - I wrote as simple a program as I could to see if what I'd installed would work:

#include <png.h>
#include <stdio.h>

int main()
    char filename[] = "clare.png";
    bool is_png;
    png_byte header[4];
    size_t number = 4;
    FILE *fp = fopen(filename, "rb");
    if (!fp)
        printf("Error opening file.\n");
        return (1);
    fread(header, 1, number, fp);
    is_png = !png_check_sig(header, number);
    if (!is_png)
        printf("Not a PNG.\n");

After reading about (a lot) I configured the active target search paths to /sw/include and /sw/lib, and I used -lpng in Other Linker Flags. I've tried changing all sorts of other things too.

The program compiles without warnings, but when I run it I get the following:

ZeroLink: unknown symbol '_png_check_sig'

libpngtest has exited due to signal 6 (SIGABRT).

If I 'Jump to Definition' for png_check_sig XCode displays the libpng header file. I've tried other functions from the library. I'm sure this must be something really simple but I'm stuck. Any help would be really appreciated.

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Posts: 5,143
Joined: 2002.04
Post: #2
Turn off ZeroLink, then fix the linker error.
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Posts: 22
Joined: 2006.04
Post: #3
Ok, so I did that, cleaned the target and on building I got a warning, but then I realised I've been making a mistake all along - the active build style seems to override any edits I make to the current target - oops. So XCode has been expecting static libraries all along...

Thanks for the help - I knew I'd done something silly.
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