threadEx1.c

// Program to create a thread. 
// The thread prints numbers from zero to n, 
// where value of n is passed from the main process 
// to the thread. The main process also waits 
// for the thread to finish first and then prints 
// from 20-24. 
#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<pthread.h>
#include<string.h>
void *thread_function(void *arg);
int i, n, j;
int main()
{
	char *m = "5";
	pthread_t a_thread; //thread declaration
	void *result;
	pthread_create(&a_thread,NULL,thread_function,m); //thread is created
	pthread_join(a_thread,&result);//process waits for thread to finish. Comments this line to see the defferance
	printf("Thread joined\n");
	for(j=20;j<25;j++)
	{
		printf("%d\n",j);
		sleep(1);
	}
	printf("thread returned %s\n",result);
}
void *thread_function(void *arg)//the work to be done by the thread is defined in the function 
{
	int sum = 0;
	n = atoi(arg);
	for(i=0;i<n;i++)
	{
		printf("%d\n",i);
		sleep(1);
	}
	pthread_exit("Done");//thread returns "Done"
}