Programming

#include <stdio.h>
#include <pthread.h>
#define NUM_THREADS 4

/* function to be executed by the new thread*/

void *PrintHello(void * threadid)
{
printf("\n %3d:Hello World!\n",threadid);
pthread_exit(NULL);
}


int main(int argc, char * argv[])
{
int *taskids[NUM_THREADS];
int rc,t;
pthread_t threads[NUM_THREADS];


for (t = 0; t < NUM_THREADS;t++)
{
taskids[t] = (int *)malloc(sizeof(int));
*taskids[t]=t;
printf("Creating thread %d\n",t);
printf(" The number in array is %d\n",*taskids[t]);
rc = pthread_create(&threads[t],NULL,PrintHello,(void *)&taskids[t]);
if (rc){
printf("ERROR;return code from pthread_create() is %d\n",rc);
exit(-1);
}
}

pthread_exit(NULL);
}


The above code is taken form the lecture notes at www.llnl.gov/computing/tutorials/pthreads under the topic passing arguments. When i run it on Sun SOlaris 9, the answe is wrong. Here is the answer: I cant detect the logic error.. PLease help.

Creating thread 0
The number in array is 0
Creating thread 1
The number in array is 1

-4195784:Hello World!
Creating thread 2
The number in array is 2
Creating thread 3
The number in array is 3

-4195780:Hello World!

-4195776:Hello World!

-4195772:Hello World!

Those numbers [-4195772] are addresses displayed as an integer. You passed a pointer to HelloWorld, a pointer is an address.

try something like this:

Code:

printf("\n %3d:Hello World!\n",*(int *)threadid);

or
printf("\n %p:Hello World!\n",threadid);

the %p can be used to print pointer address on most unix c compilers.