qsort() function not working as expected in c

Question

I'm trying to write a simple string sorting program using qsort().(inspired from program in qsort manual in Linux)

This is my code.

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

void disparray(int i,char words[10][20]);
int compare_strings(const void *a,const void *b);

int main()
{
    int index=0;
    char words[10][20];
    while(fgets(words[index],20,stdin)) //take array of strings as input from stdin
    {
        if (words[index][0]=='\n') break;
        words[index][ strlen(words[index]) - 1 ] = '\0'; //to remove trailing newline
        index++;
        if (index==10)break;
    }
    disparray(index,words);
    qsort(words,index,sizeof(char*),compare_strings);
    disparray(index,words);
    return 0;
}

int compare_strings(const void *a,const void *b)
{
    //return strcmp(*(char **)a, *(char**)b); // this is what I think is correct command, but it causes segfault.
    return strcmp(a,b);                         // This gives wrong result.
}

void disparray(int index,char words[10][20])
{
    int f=0;
    while(f<index)
        {
            printf("%s\n",words[f]);
            f++;
        }
}

But I am having problems with the qsort function and the comparing function. The output I get is not sorted in the current version of my program. This is what I get

./trial <words
one
two
three
four
five
six
seven
eight
nine
ten

0�one
three
four
five
six
seven
eight
nine
ten

how do I fix it?