Help with linked list in C Post: 302509541

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Top Forums Programming Help with linked list in C Post 302509541 by disaster on Thursday 31st of March 2011 03:49:55 AM

Old

03-31-2011

Registered User

I think the problem is, that you only work on the malloc'ed memory locally within the function.
You give add_client a pointer of type client. This is given by call by value, i.e. assigning the pointer a newly malloc'ed memory will not assign this memory to the pointer in the main function! Therefore your client *current is pointing to an undefined memory location even after call of add_client.

Better do this:

Code:

client *add_client(char *username, client *head, int *client_socket_fd) {
    client *current;
    current = (client *)malloc(sizeof(client)); 
    current->client_name = username;
    current->next = head;
    current->client_socket_fd = *client_socket_fd;
    return current;
}

Furthermore: What are you willing to achieve with:
head = current;
current = head
?

disaster

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LEARN ABOUT DEBIAN

gearman_client_set_workload_malloc_fn

GEARMAN_CLIENT_SET_WORKLOAD_MALLOC_FN(3)			     Gearmand				  GEARMAN_CLIENT_SET_WORKLOAD_MALLOC_FN(3)

NAME

       gearman_client_set_workload_malloc_fn - Gearmand Documentation, http://gearman.info/

SYNOPSIS

       #include <libgearman/gearman.h>

       gearman_client_st

       gearman_task_context_free_fn

       int gearman_client_timeout(gearman_client_st *client)

       void gearman_client_set_timeout(gearman_client_st *client, int timeout)

       void *gearman_client_context(const gearman_client_st *client)

       void gearman_client_set_context(gearman_client_st *client, void *context)

       void gearman_client_set_workload_malloc_fn(gearman_client_st *client, gearman_malloc_fn *function, void *context)

       Deprecated since version 0.23: Use gearman_allocator_t

       void gearman_client_set_workload_free_fn(gearman_client_st *client, gearman_free_fn *function, void *context)

       Deprecated since version 0.23: Use gearman_allocator_t

       void gearman_client_task_free_all(gearman_client_st *client)

       void gearman_client_set_task_context_free_fn(gearman_client_st *client, gearman_task_context_free_fn *function)

       Link with -lgearman

DESCRIPTION

       gearman_client_st is used for client communication with the server.

       gearman_client_context() and gearman_client_set_context() can be used to store an arbitrary object for the user.

       gearman_client_set_task_context_free_fn() sets a trigger that will be called when a gearman_task_st is released.

       gearman_client_timeout() and gearman_client_set_timeout() get and set the current timeout value, in milliseconds, for the client.

       Normally   malloc(3)   and   free(3)   are  used  for  allocation  and  releasing  workloads.  gearman_client_set_workload_malloc_fn()  and
       gearman_client_set_workload_free_fn() can be used to replace these with custom functions. (These have been  deprecated,	please	see  gear-
       man_allocator_t for the updated interface.

       gearman_client_task_free_all() is used to free all current gearman_task_st that have been created with the gearman_client_st.

       Warning
	      By  calling  gearman_client_task_free_all()  you can end up with a SEGFAULT if you try to use any gearman_task_st that you have kept
	      pointers too.

RETURN VALUE

       gearman_client_timeout() returns an integer representing the amount of time in milliseconds. A value of -1 means an infinite timeout value.
       See poll(3) for more details.

HOME

       To find out more information please check: http://gearman.info/

       See also

	      gearmand(8) libgearman(3) gearman_client_create(3)

AUTHOR

       Data Differential http://www.datadifferential.com/

COPYRIGHT

       2012, Data Differential, http://www.datadifferential.com/

0.33								   May 04, 2012 			  GEARMAN_CLIENT_SET_WORKLOAD_MALLOC_FN(3)