Extract a substring from a string from specified position

Extract a substring (substr) of length n from a string (str) from specified position (pos)

#include<stdio.h>

void main()

{

                char str[20], substr[20];

                int n, pos, i, j=0;

                printf("\nEnter the string:");

                gets(str);

                printf("\nEnter the position:");

                scanf("%d", &pos);

                printf("\nEnter the length of substring:");

                scanf("%d", &n);

                i = pos;

                while(str[i] != '\0'  &&  n>0)

                {

                                substr[j] = str[i];

                                i++;

                                j++;

                                n--;

                }

                substr[j] = '\0';

                printf("\nThe substring is:");

                puts(substr);

}

Output:

Enter the string:               hello hii abc

Enter the position:          2

Enter the length of substring:     5

The substring is:               llo h