从矩阵打印超过15行后，表格崩溃

Question

我必须将每个单词与字符串分开，并且每个单词必须在矩阵中排成一行。一个单词由空格，制表符，换行符分隔，然后程序打印每一行。矩阵的末尾用0标记。

#include<stdio.h>
#include<stdlib.h>

char    *ft_strdups(char *str, int start, int to)
{
    char *p;
    int i;

    i = 0;
    if (to < start)
        return (NULL);

    p = (char*) malloc(sizeof(char)*(to - start + 1));
    if (!p)
        return (NULL);

    while(start < to && str[start])
    {
        p[i] = str[start];
        start++;
        i++;
    }
    p[i] = '\0';
    return (p); // This function dynamicaly allocates the string
}

int     tw(char *str)
{
    int i;
    i = 0;
    while (str[i] != '\t' && str[i] != '\n' && str[i] != ' ' && str[i])
        i++;
    return (i); // This function traverses the word and returns the length
}

int     nb_words(char *str) // counts the numbers of words
{
    int i;
    int k;
    k = 0;
    while (str[i] != '\0')
    {
        if(str[i] != '\t' && str[i] != '\n' && str[i] != ' ' && str[i])
        {
            i = i + tw(str + i);
            k++;
        }
        else
            i++;
    }
    return (k);
}

char    **ft_split_whitespaces(char *str)
{
    int     i;
    char    **p;
    int     j;
    j = 0;
    i = 0;
    p = (char**)malloc(sizeof(char) * (nb_words(str) + 1));
    while(str[i] != '\0')
    {
        if (str[i] != '\n' && str[i] != '\t' && str[i] != ' ')
        {
            p[j] = ft_strdups(str, i, i + tw(str + i));;
            j++; // here is the allocation
            i = tw(str + i) + i;
        }
        else
            i++;
    }
    p[j] = 0;
    return (p);
}

int     main(int ac, char **av)
{
    char **p;
    int i;
    i = 0;
    if(ac != 2)
        return(0);
    p = ft_split_whitespaces(av[1]);
    while (p[i])
    {   
        printf("%s\n",p[i]);
        i++;
    }
}

问题在于，如果我给出一个超过16个单词的字符串（例如：./a.out "1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20"），它会崩溃，从而导致打印一些非ascii字符而不是我之前的单词。