Thread: Pointer question

I wrote the following program:

Code:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <pthread.h>
#define perror2(s,e) fprintf(stderr,"%s: %s\n",s,strerror(e))

int nthr;
int cbits;
pthread_mutex_t mtx1=PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t begin=PTHREAD_COND_INITIALIZER;

void *worker(void *iter) {
    int i,err;
    printf("I am worker with id %d , iter=%d\n",pthread_self(),(long int *)iter);           /* Here shouldn't it be *(long int *)iter ?*/
/*    for(i=0;i<nthr;i++)
	if(err=pthread_join(tids[i],NULL)) {
	    perror2("pthread_join",err);
	    exit(1);
*///	}
    pthread_exit(NULL);
}

void *controller(void *ids) {
    int i;
    int *wids=(int *)ids;
    long int terms;
    
    srand48((long int)time(NULL));
    terms=lrand48()%(long int)(pow(double(2),(double)cbits));
    printf("Controller :%d",cbits);
    printf(".Workers id's :");
    for(i=0;i<nthr;i++)
	printf(" , %d",*wids++);  /* Here it is as it should be */
    printf("\n");
    pthread_exit(NULL);
}

main(int argc,char** argv) {
    int i,err;
    long int iter;
    pthread_t *wids,cid;

    cbits=atoi(argv[3]);
    if(argc!=4) {
        printf("Usage: pibythr <nthr> <wbits> <cbits>\n");
        exit(1);
    }
    nthr=atoi(argv[1]);
    if((wids=(pthread_t *)malloc(nthr*sizeof(pthread_t)))==NULL) {
	perror("malloc");
	exit(1);
    }
    srand48((long int)getpid());
    for(i=0;i<nthr;i++) {
	iter=lrand48()%(long int)(pow((double)2,(double)atoi(argv[2])));
	if(err=pthread_create(wids+i,NULL,worker,(void *)iter)) {
	    perror2("pthread_create",err);
	    exit(1);
	}
    }
    if(err=pthread_create(&cid,NULL,controller,(void *)wids)) {
	perror2("pthread_create",err);
	exit(1);
    }
/*    if(err=pthread_join(cid,NULL)) {
	perror2("pthread_join",err);
	exit(1);
    }
*/    printf("main:All threads terminated\n");
    pthread_exit(NULL);
}

My question is about the two lines with the comments next to printf's.
In the first one if i put *(long int*)iter instead of (long int*)iter it prints "Segmentation fault"
Why is this happening?Why does it work properly by writing (long int*)iter?
Shouldn't this line be similar to the second with the *wids?

Thank you in advance.

>>if(err=pthread_create(wids+i,NULL,worker,(void *)iter)) {

On this line you need to pass the address of iter using &.

if(err=pthread_create(wids+i,NULL,worker,(void *)&iter)) {