Re: libpng problem -- png_read_destroy

[Charles Wilson <cwilson at ece dot gatech dot edu>]

Two solutions:

a) link using 'gcc -static'.  You must also define ZLIB_STATIC (see
/usr/doc/Cygwin/libpng-x.x.x.README).

OR 

b) DON'T define PNG_STATIC.  

--Chuck


"Jong B. Lee" wrote:
> 
> Happy New Year !!
> 
> I'm writing a program using png library.
> 
> But, gcc complains that   png_read_destroy  and  png_write_destroy  are  undefined.
> 
> How can I fix it?
> 
> I have the latest and clean cygwin installed.
> 
> Here's a sample c file and link error :
> 
> ------------------------------------
> /* sample   png.c */
> #include <png.h>
> 
> int main()
> {
>    #ifdef __CYGWIN__
>    #define PNG_STATIC
>    #endif
> 
>    png_structp pp;
>    png_infop info;
>    png_read_end(pp, info);
>    png_read_destroy(pp, info, NULL);
>    png_write_destroy (pp);
> 
>    return 0;
> }
> -------------------------------------
> $ gcc -W -g png.c  -lpng  -o png
> 
> /c/WINDOWS/TEMP/ccFXASfF.o(.text+0x30): undefined reference to `png_read_destroy'
> /c/WINDOWS/TEMP/ccFXASfF.o(.text+0x3f): undefined reference to `png_write_destroy'
> collect2: ld returned 1 exit status
> ===============================

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