Posix Threads

For a school assignment i'm trying to write a program that creates 50 threads; each thread puts their ID in every slot of a custom, 10000 slot vector-class and then checks to see if it is consistent. This is my code:

#include "Vector.hpp"
#include <stdio.h>
#include <pthread.h>

void *writer(void *ptr);
Vector johndoe;

int main()
{
	int j, k;
	
	
	pthread_t test[50];
	
	for (j=0 ; j<50 ; j++)
	{
		pthread_create(test[j], NULL, writer, (void*) &j);
	}
	
	for (k=0 ; k<50 ; k++)
	{
		pthread_join(test[k], NULL); 
	}
	
}

void *writer(void *ptr)
{
	int _id = *(int*) ptr; 
	if (!johndoe.setAndTest(_id))
	{
		printf("Thread #%d: Vector is inconsistent!!\n", _id); 
	}
	
	else if((johndoe.setAndTest(_id)))
	{
		printf("Thread #%d: Vector is consistent\n", _id); 
	}
	
}

But this is my output:

Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #24: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #35: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!
Thread #50: Vector is inconsistent!!

What am i doing wrong??

Hope you can help

Could you also post your custom Vector code..
What's interesting is that what should be covering code if/else seems to be being skipped (there is no consistent/not consistent for 23 for ex.)
Is your Vector code using setjmp or something?

regards, Alex

Hey Alex!

Thanks for your reply!

I realised the problem was with sending a pointer to the "j"-variable used in the for-loop. It keeps increasing while the threads are running, so naturally it simply ends up at 50 and prints that out for the rest!

i solved it by declaring an int-array containing the nr. from 1 to 50 and sending those instead.

another problem i have now is, i have a 1-second sleep in the "writer"-function, but it seems to be ingnored?

Where are you calling the sleep func, could you post updated writer function..

I cordially suggest that the person you should be discussing this with is your teacher, so that he or she can gauge the confusion of both you and all of the other students in your class. (Otherwise, how is the teacher supposed to know?)