[review] [PyKDE] Help on wrapping a C library

Jim Bublitz jbublitz at nwinternet.com
Mon May 23 22:12:05 BST 2005

On Monday 23 May 2005 11:38, huaicai wrote:
> Hi all,
> I was trying to use SIP to wrap a C library GTS(gnu triangular surface). I
> am new to the SIP tool, so before wrapping GTS, I am learning to wrap a
> simple C libary just like the C example(word) in the SIP reference guide.
> I implemented the "Word" libary in C and a C test program works fine by
> using the libary. I got a "segmentation fault" error when I call the
> reverse() in python as follows:
>               import word
>               w = word.create_word("How are you?")
>               print word.reverse(w)
> I added another reverse function into the "word" library like: "char
> *myReverse(const char *w);". It works fine in python when I do this:
>               print word.myReverse("How are you?")
> Please see the C source/header file and SIP specification file in the
> attachments. Can any one tell me what's wrong?
> Thank you very much! I really appreciate your help.
> Huaicai

It might not strictly be required, but I'd add:

    #include <word.h>

after the %CModule line (although it seems like you'd get compile errors if it 
was really necessary - might depend on whether sip generated code is 
concatenated for compiling or not).

You might also try:

Word *create_word(const char *);
char *reverse(Word *);
char *myReverse(const char *);

removing "struct" in two places (not sure if it's required or makes a 
difference as far as sip is concerned - I believe it's not necessary though).

Also, in Python, try printing w.the_word before calling reverse.

You could also try making Word a class:

class Word
    char *the_word;

At one time (long ago) I had problems doing structs with sip, but I think 
that's been fixed for quite a while.

Otherwise, I don't see any obvious errors in the sip file. I'd also look at 
how the module is linked and if the .so file being wrapped can be found at 


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