C 구조체에서 가변길이 문자열 처리.

#ifndef __HDSTR_H__
#define __HDSTR_H__
 
void            hds_init(unsigned int align);
const char *    hds_push(const char *str);
const char *    hds_first();
const char *    hds_next(const char *pos);
void            hds_clear();
 
unsigned int    hds_count();
 
#endif

#include "hdslist.h"
 
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <memory.h>
 
static struct
{
    unsigned int len;
    unsigned int max;
    unsigned int count;
    unsigned int align;
    char *buf;
    char *pos;
} global;
 
static void extend()
{
    char *buf = (char *)realloc(global.buf, global.max + global.align);
    global.max += global.align;
    if (buf != global.buf)
    {
        memcpy(buf, global.buf, sizeof(char)*global.max);
        global.buf = buf;
    }
}
 
void hds_init(unsigned int align)
{
    global.align = align;
    global.buf = (char *)calloc(align, sizeof(char));
    global.pos = global.buf;
    global.max = align;
    global.len = 0;
    global.count = 0;
}
const char *hds_push(const char *str)
{
    const char *hds;
    const size_t len = strlen(str);
 
    while (global.max - global.len < len)
        extend();
 
    strcpy(global.pos, str);
    hds = global.pos;
 
    global.pos += len + 1;
    global.len += len + 1;
    ++global.count;
 
    return hds;
}
const char *hds_first()
{
    return global.buf;
}
const char *hds_next(const char *pos)
{
    while (*pos++)
        ;
    return pos;
}
void hds_clear()
{
    if (global.buf)
        free(global.buf);
    hds_init(global.max);
}
 
unsigned int hds_count()
{
    return global.count;
}

#include <stdio.h>
#include "hdslist.h"
 
void show_list();
 
int main(void)
{
    const char *arr[10];
    int ac = 0;
 
    hds_init(10);
 
    hds_push("Hello, world!");
    hds_push("My name is DoYeong Han!");
    hds_push("See ya!");
    show_list();
 
    hds_push("Hello again, friend!");
    show_list();
 
    hds_clear();
    show_list();
 
    hds_push("string 1");
    hds_push("string 2");
    show_list();
 
    return 0;
}
 
void show_list()
{
    unsigned int i;
    const char *pos;
    unsigned int count;
 
    count = hds_count();
    for (i=0, pos=hds_first(); i<count; ++i, pos=hds_next(pos))
        printf("%d: %s\n", i, pos);
    puts("");
}