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List:       pykde
Subject:    [PyKDE] Help on wrapping a C library
From:       "huaicai" <huaicai () nanorex ! com>
Date:       2005-05-23 18:38:12
Message-ID: 20050523183813.8367.qmail () mail3 ! infinology ! net
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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 


["word.c" (word.c)]

#include "word.h"
#include <string.h>
#include <malloc.h>

struct Word *create_word(const char *w) {
        struct Word *wd;
        wd = (struct Word*)malloc(sizeof(struct Word));
        
        wd->the_word = (char *)malloc((strlen(w) + 1)*sizeof(char));
        strcpy(wd->the_word, w);
        
        return wd;
}

char *reverse(struct Word *word) {
        int ii, len;
        char *newStr;
        char *w = word->the_word;
        
        len = strlen(w);
        newStr = (char *)malloc((len + 1)*sizeof(char));
        for (ii=0; ii<len; ii++)
         newStr[ii] = w[len-ii-1];
        newStr[len] = '\0';
        
        free(word->the_word);
        free(word);
        
        return newStr;
}

char *myReverse(const char *w)  {
        int ii, len;
        char *newStr;
        
        len = strlen(w);
        newStr = (char *)malloc((len + 1)*sizeof(char));
        for (ii=0; ii<len; ii++)
         newStr[ii] = w[len-ii-1];
        newStr[len] = '\0';
        
        return newStr;
}

["word.h" (word.h)]

#ifndef WORD_H
#define WORD_H

/* Define the interface to the word library. */

struct Word {
    char *the_word;
};

struct Word *create_word(const char *w);
char *reverse(struct Word *word);
char *myReverse(const char *w);

#endif

["word.sip" (word.sip)]

/* Define the SIP wrapper to the word library. */

%CModule word 0

struct Word {

%TypeHeaderCode
#include <word.h>
%End

    char *the_word;
};

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

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