warning:assignment makes integer from pointer without a cast.

[sanzou321]

I'm trying to make the function *searchterm_generator return an array of pointers to strings but
I get the warning at store[j] = query_term (where i try to make each pointer in store point to the first character of the string search_term)
I didn't find any answer to my problem and hence had to post it up.

char
*searchterm_generator(const char *query, int k){
	int query_len = strlen(query);
	assert(k <= query_len);
	int n = k;
	char search_term[k+1];            /* +1 to store null char */
	char *store = malloc(sizeof(char)*k*query_len);
	int record_number = 0; int i; int j;
        for(j = 0;j<n;j++){
          for (i = 0; i<n ; i++){
		search_term[i] = query[i];
		if(i == (n-1)){
		      search_term[k] = '\0';
                }
        }
	  store[j] = search_term;
        }
        return store;
}

[abhishekm71]

store and search_term are a pointers to char and store[j] is a char. you are assigning a pointer address to a char value.

also, in your statement char search_term[k+1]; the value in [] should be a constant.

[sanzou321]

thanks abhiskekm71, ah yes that makes sense.
k remains constant throughout the function, so technically the value in [] is a constant right?

Could you suggest a way to make each pointer in store point to the first character of the string search_term.

[abhishekm71]

maybe you can try:

EDIT: code deleted.

Also, if k does not change, you should declare it as a const in your function prototype. Even after that i don't think its valid to assign an array of k or k+1 length the way its done in your code.

[sanzou321]

Hmm, i now get an error "lvalue required as left operand of assignment "
for tempPtr++ = search_term;

Sorry i'm a newbie to coding and pointers.

[abhishekm71]

The code is not working because store is an array of chars and not pointers. Please tell me what you want to do and only then a suitable algorithm can be suggested.

EDIT: I think, what you want is maybe store[j] = search_term[0];

[sanzou321]

I want my function to return an array of pointers, each pointing to a whole string, so store[0] can be a string of length 4 and everytime as j changes, the next pointer in store can hold the same (or different string if i tweak my code a little), but the general idea is that i want to return many strings from this function.

[abhishekm71]

the best way would be to declare a vector of std::string types. something like:

std::vector<std::string> searchterm_generator(const char *query, const int k){
  int query_len = strlen(query);
  assert(k <= query_len);
  int n = k;
  std::vector<std::string> store;
  std::string search_term; 
//  char *store = malloc(sizeof(char)*k*query_len);
  int record_number = 0; int i; int j;
  for (j=0; j<n; j++) {
    for (i = 0; i<n ; i++)
      search_term[i] = query[i]; // no need for NULL character
    store.push_back(search_term);
   }
  return store;
}

ofcourse you will have to #include <string> and <vector>

[sanzou321]

arent classes only used in c++, i'm required to do this only in C O.o

[abhishekm71]

well i'm not too confident about C but you can try the following. However, please re-check the syntax, and more importantly memory allocation/deallocation scope issues.

char **searchterm_generator(const char *query, int k){
	int query_len = strlen(query);
	assert(k <= query_len);
	int n = k;
	char search_term[k+1];            /* +1 to store null char */
	char **store = (char**) malloc (sizeof(char*)*k); // pointer to pointer of char
	int record_number = 0; int i; int j;
               for(j = 0;j<n;j++) {
                    for (i = 0; i<n ; i++){
                               search_term[i] = query[i];
                               if(i == (n-1)){
                                  search_term[k] = '\0';
                              }
                    }
                    *store = search_term;
                    store++;
              }
              return store;
}

EDIT: there is one flaw, search_term will go out of scope once the function ends and so all the elements in the store array will point to garbage.

[sanzou321]

yes all my pointers point to the last search_term, which means all the pointers, except the last one, point to garbage, is there anyway around that?

[abhishekm71]

you can pass search_item as a parameter to the function. That way, value pointed by search_item shall belong to the calling function and will not go out of scope.

Also, at least in your present function, search_term does not seem to have any use. You could as well assign the *store pointer, the value of query. Note that value pointed by query address does not go out of scope.

[sanzou321]

what i ended up doing was add all the strings to char arrays in a struct using store as an array of pointers to structs. But thanks for your input abhishekm71, appreciated :D