c - Passing structures in pthread -

i trying pass structure when creating thread not seem work correctly!

here structure:

struct analyse_data {     int verbose; //should 1 or 0 }; 

note verbose can 1 or 0 , nothing else.

here method being called (note can called multiple times method):

void dispatch(struct pcap_pkthdr *header, const unsigned char *packet,         int verbose) {      static bool thread_settings_initialised = false;      printf("verbose: %d\n", verbose); //prints 1 or 0      //only run first time dispatch method runs     if (thread_settings_initialised == false){         thread_settings_initialised = true;          //...              //set mutex appropriate variables remain thread safe         //...          //set attr threads "detached"         pthread_attr_init(&attr);         pthread_attr_setdetachstate(&attr, pthread_create_detached);          //set pthread_cond_init         //...     }      //put parameters struct can sent in thread     struct analyse_data data;     data.verbose = verbose;      //...      pthread_t tid;     printf("data.verbose: %d\n", data.verbose); //this prints 1 or 0     int rc = pthread_create( &tid, &attr, bar, (void *) &data);     if (rc) {         printf("error; return code pthread_create() %d\n", rc);         exit(-1);     }  } 

and method thats being called thread:

void analyse(void *thread_data) {     struct analyse_data *data;     data = (struct analyse_data *) thread_data;     int verbose = data->verbose;     printf("verbose =  %d\n", verbose ); //prints weird numbers -547845... } 

as can see comments, value of verbose changes when being used inside method. why? doing wrong?

many thanks!

update (thanks js1) updated code use pointer:

void dispatch(struct pcap_pkthdr *header, const unsigned char *packet,         int verbose) {      static bool thread_settings_initialised = false;      printf("verbose: %d\n", verbose); //prints 1 or 0      //...      //put parameters struct can sent in thread     struct analyse_data *data = malloc(sizeof(struct analyse_data)); //new     data->verbose = verbose;      //...      pthread_t tid;     printf("data.verbose: %d\n", data.verbose); //this prints 1 or 0     int rc = pthread_create( &tid, &attr, bar, (void *) data);     //... } 

but analyse() method outputs 0, when verbose 1!

you should not pass stack variable pthread_create. notice data local function dispatch , out of scope when dispatch returns. should instead either use malloc allocate data, or use static or global variable.

if use malloc method, this:

struct analyse_data *data = malloc(sizeof(struct analyse_data)); data->verbose = verbose;  int rc = pthread_create( &tid, &attr, bar, data); 

you must remember not call free on data dispatch. memory should "belong" thread, should call free on data thread when done using contents of data.