/* Exercise 4-1 of _The C Programming Language_: "write the function 
strrindex(s,t), which returns the position of the rightmost occurence of t 
in s, or -1 if there is none. 12/03/01. */

#include <stdio.h>
#define MAXLINE 1000
#define DEBUG 1


/* strrindex: returns index of rightmost occurence of t in s, -1 if none. 
searches from back to front of string. */
int strrindex(char s[], char t[], int n)
{
  int i, j, k;

  if (DEBUG) {
    printf(" DEBUG: in strrindex, n = %i \n", n);
    printf(" DEBUG:   s = %s \n", s);
    printf(" DEBUG:   t = %s \n", t);
  }

  for(i = n; s[i] != '\0'; i--)
    {
      if (DEBUG)
	printf(" DEBUG:  i loop, i = %i, s[i] = '%c' \n", i, s[i]);
      
      for(j = i, k = 0; (t[k] != '\0') && (s[j]==t[k]); j++, k++)
	if (k < n && t[k] =='\0')
	  return i;
    }
  return -1;
}

/* getline: lifted straight from the book. gets line into s, returns length. */
int getline(char s[], int lim)
{
  int c, i;
  i = 0;
  while((--lim > 0) && ((c=getchar()) != EOF) && (c != '\n'))
    s[i++] = c;
  if (c == '\n') 
    s[i++] = c;
  s[i] = '\0';
  return i;
}

main()
{
  char pattern[] = "mus";
  char line[MAXLINE];
  int found = 0;
  int n, m;
  n = getline(line, MAXLINE);

  if (DEBUG) 
    printf("  DEBUG: input line = '%s' with %i chars. \n", line, n );

  m = strrindex(line, pattern, n);

  if (m >= 0)
    printf("'mus' found in %s at %i\n", line, m);
}