Question

I have already implemented some of the recommendations before in Code Review. I also improved my code by using pointers. However, what is wrong with address incrementation part below squeezed_str++? It seems that address is not incrementing. Please advise.

PS. substring() function is working. 🙂

char *squeeze (char *str, int start_index, int end_index, char *ref_str) {
     char *substr;
     substr = malloc (sizeof (*substr));
     if (substr == NULL) {
          printf ("Unable to allocate memory.\n");
          exit (EXIT_FAILURE);
     }

     char *squeezed_str;
     squeezed_str = malloc (sizeof (*squeezed_str));
     if (squeezed_str == NULL) {
          printf ("Unable to allocate memory!\n");
          exit (EXIT_FAILURE);
     }

     substr = substring (str, start_index, end_index);
     int substr_len = strlen (substr);
     int refstr_len = strlen (ref_str);

     char chr1, chr2; chr1 = chr2 = '\0';

     for (int i = 0; i < substr_len; i++) {
          chr1 = *(substr+i);
          for (int j = 0; j < refstr_len; j++) {
               chr2 = *(ref_str + j);
               if (chr1 == chr2) {
                    break;
               }
          }
          if (chr1 != chr2) {
               *squeezed_str = *(substr+i);
               squeezed_str++;
          }     
     }

     return squeezed_str;
 } /* end of squeeze() */

Answer 1

Some improvements with inline advice, not tested:

char *squeeze (char *str, int start_index, int end_index, char *ref_str) {
     char *substr = substring (str, start_index, end_index);
         //do not malloc here!, you are doing an assignment later on, so memory leak
         //infact might as well move assignment right here

     char *squeezed_str;
     squeezed_str = malloc (strlen(str)+1); //+ 1 one for null terminator
     if (squeezed_str == NULL) {
          printf ("Unable to allocate memory!\n");
          exit (EXIT_FAILURE);
     }

     int substr_len = strlen (substr);
     int refstr_len = strlen (ref_str);
     int squeezeStrIdx = 0;

     for (int i = 0; i < substr_len; i++) {
          char chr1 = substr[i]; //using index accessing is nicer
                                 //moved the scope of the variable in
          char chr2 = '\0'; //reduced variable scope, benefit is now resets each loop
          for (int j = 0; j < refstr_len; j++) {
               chr2 = ref_str[j];
               if (chr1 == chr2) {
                    break;
               }
          }
          if (chr1 != chr2) {
               squeezed_str[squeezeStrIdx] = chr1;
               squeezeStrIdx++; //if you modify squeezed_str,
                                //how do you expect to return it at end of method?
          }     
     }

     //this is to null terminate the squeezed_str
     squeezed_str[squeezeStrIdx] = '\0';

     return squeezed_str;
 } /* end of squeeze() */