Issues with malloc, returning pointer, conflicting types

I'm debugging an assignment due very soon, please help ASAP.


The error is:

Assignment makes pointer from integer without a cast.

So, apparently add_group returns an int, yet the return type is char *


this is the block of code that calls the function which returns a char * pointer:

buffer is delcared as this -------> char *buffer;

Code:

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} else if (strcmp(cmd_argv[0], "add_group") == 0 && cmd_argc == 2) {
        buffer = add_group(group_list_addr, cmd_argv[1]); 
        printf("%s", buf);

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This is the block of code that is add_group:

Code:

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char *add_group(Group **group_list_ptr, const char *group_name) {
   
   
  if (find_group(*group_list_ptr, group_name) == NULL) {
        //malloc space for new group
        Group *newgrp;
        char *groupSucc;
        char *groupFail;
        if ((groupSucc = malloc(sizeof(group_name) + 21)) == NULL) {
            perror("Error allocating space for add_group success message");
            exit(1);
        strcpy(groupSucc, "Group ");
        strcat(groupSucc, group_name);
        strcat(groupSucc, " added");
        if ((newgrp = malloc(sizeof(Group))) == NULL) {
          perror("Error allocating space for new Group");
          exit(1);
        }
        // set the fields of the new group node
        // first allocate space for the name
        int needed_space = strlen(group_name) + 1;
        if (( newgrp->name = malloc(needed_space)) == NULL) {
          perror("Error allocating space for new Group name");
          exit(1);
        }
        strncpy(newgrp->name, group_name, needed_space);
        newgrp->users = NULL;
        newgrp->xcts = NULL;
        newgrp->next = NULL;
        // Need to insert into the end of the list not the front
        if (*group_list_ptr == NULL) {
          // set new head to this new group -- the list was previously empty
          *group_list_ptr = newgrp;
          return groupSucc; 
        }  else {
        // walk along the list until we find the currently last group
          Group * current = *group_list_ptr;
          while (current->next != NULL) {
            current = current->next;
          }
          // now current should be the last group
          current->next = newgrp;
          return groupSucc;
        }
    } else {
            // group EXISTS
            if ((groupFail = malloc(sizeof(group_name) + 21)) == NULL) {
                perror("Error allocating space for add_group failure message");
                exit(1);
            }
            strcpy(groupFail, "Group ");
            strcat(groupFail, group_name);
            strcat(groupFail, " already exists");
            return groupFail;
    }
}

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You probably need to forward declare the function, e.g., in a header file.

Taking out the * on char *buffer; fixed it

Still not sure whether I am returning what I actually want. The print statement thinks that buffer is an int?!!

Quote:

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Originally Posted by pointingmachine

Taking out the * on char *buffer; fixed it

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Not likely. The compiler is not complaining, but your code is most certainly incorrect.

As I said, the problem is likely because you did not declare the function before use. For example, you might be calling the function in the main function, whereas the function is defined after the main function.