C : Array of strings - Can input only n-1 strings for an input size of n

Question

I have to sort strings in a lexicographical order using the Bubble Sort technique without using any library functions. I have written the following code which is working fine in sorting the strings.

But the problem is that if I give n as the input (say n = 4), I can enter only n-1 strings (only 3 strings). The problem can be solved by running the for loops from 0 to n, but that isn't a logical solution.

What am I doing wrong here?

#include <stdio.h>
#include <string.h>
#include <malloc.h>
void swap(int indx[], int j)
{
    int temp;
    temp = indx[j];
    indx[j] = indx[j+1];
    indx[j+1] = temp;
}
void sort(char **str, int indx[], int n)
{
    int i, j, k;
    for(i=0; i<n; i++)
    {
        for(j=0; j<n-i-1; j++)
        {
            k = 0;
            while(str[j][k] != '\0')
            {
                if((str[indx[j]][k]) > (str[indx[j+1]][k]))
                {
                    swap(indx, j);
                    break;
                }
                else if((str[indx[j]][k]) < (str[indx[j+1]][k]))
                    break;
                else
                    k++;
            }
        }
    }
}
void display(char **str, int indx[], int n)
{
    int i;
    printf("Sorted strings : ");
    for(i=0; i<n; i++)
        printf("%s\n", str[indx[i]]);
}
int main(void)
{
    char **str;
    int n, i, j, *indx;
    printf("Enter no. of strings : ");
    scanf("%d", &n);
    str = (char **) malloc (n * (sizeof(char *)));
    indx = (int *) malloc (n * sizeof(int));
    for(i=0; i<n; i++)
        str[i] = (char *)malloc(10 * sizeof(char));
    printf("Enter the strings : ");
    for(i=0; i<n; i++)
    {
        gets(str[i]);
        indx[i] = i;
    }
    sort(str, indx, n);
    display(str, indx, n);
}

Answer 1

The problem is your use of scanf(). When you do scanf("%d", &n), the scanf() function reads input until it finds an integer, and puts the value into n. However, when you entered that integer, you didn't just type '4', you typed '4' and pressed Enter. And the newline is still in the input buffer. The gets() function, on the other hand, reads input up to and including the first newline, and the newline character is discarded. So when you're reading the input strings, the gets call to gets() reads the newline, and returns immediately. And then, the first string that you enter is read by the second call to gets()...

Incidentally, The gets() function should never, ever, under any circumstances, ever be used for real programs, because it doesn't allow you to limit input. Better would be to use fgets(). fgets(str[i], BUFFERSIZE-1, stdin).