How do I complete K&R Exercise 2-4?

Question

I\'m learning how to write programs in C using the k&r book (The C Programming Language) and I have a problem with one of the exercises. It\'s asking me to detect and re

Answer 1

You don't need a fancy binary search to do the job. What you need is a double for loop that check for occurrence of each char in one string in another, and copy the non-occurring chars into a third char array (which is your result).

Code can be something like the following (not tested!):

char *s1, *s2, *result; /* original strings and the result string */
int len1, len2; /* lengths of the strings */
for (i = 0; i < len1; i++) {
   for (j = 0; j < len2; j++) {
     if (s1[i] == s2[j]) {
       break;
     }
   }
   if (j == len2) {  /* s1[i] is not found in s2 */
     *result = s1[i]; 
     result++; /* assuming your result array is long enough */
   }
}