stringbuf.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "stringbuf.h"
#include <ctype.h>

stringbuf *sb_create(int length){
    if (length < 10) {
        length = 10;
    }
    stringbuf *list = malloc(sizeof(stringbuf));
    if (!list) {
        return 0;
    }
    /** 0 out the fields for error check later */
    list->used = 0;
    list->length = 0;
    list->data = 0;

    list->data = malloc(sizeof(char)*length);
    if (!list->data) {
        return 0;
    }
    list->length = length;
    list->data[0] = '\0';
    list->used = 0;
    return list;
}

void sb_destroy(stringbuf *list) {
    free(list->data);
    free(list);
}

int sb_append(stringbuf *list, char item){
    if (list->used == list->length - 1){
        int new_len = 2*(list->length - 1) + 1;
        char *p = realloc(list->data, sizeof(char)*new_len);
        if (!p){
            return EXIT_FAILURE;
        }
        list->length = new_len;
        list->data = p;
    }
    (list->data)[list->used] = item;
    list->used += 1;
    (list->data)[list->used] = '\0';
    return EXIT_SUCCESS;
}

char *sb_get_lower_word(stringbuf *list){
    char *lower_word = malloc(sizeof(char)*(list->used + 1));
    /** returns NULL */
    if (!lower_word) {
        return 0;
    }
    for (int i = 0; i < list->used; i += 1) {
        /** uppercase alphabet will be lowercased, all else is returned same as is */
        lower_word[i] = tolower((list->data)[i]);
    }
    lower_word[list->used] = '\0';
    list->used = 0;
    list->data[0] = '\0';
    return lower_word;
}