Creation of no. of threads & synchronized by pthread_join

/MY PROGRAM ARE COMPILED IN FEDORA15 ..WITH 4.6 gcc compiler...../

/*In which program i have created 4 diffrent threads doing diffrent work...excuted o    ne by one...by waiti//ng each thread by using pthread_join or we can say ...join cre    ated thread with creating thread...nw main thread will wait untill created thread do     not finishes*/

  2 #include<stdio.h>

  3 #include<stdlib.h>

  4 #include<pthread.h>

  5 void* thread_fun1(void*);

  6 void* thread_fun2(void*);

  7 void* thread_fun3(void*);

  8 void* thread_fun4(void*);

  9 int main()

 10     {

 11         int lv;

 12         void* retval;

 13         char *message="THIS IS LINUX";

 14         pthread_t tid1,tid2,tid3,tid4;

 15         lv=pthread_create(&tid1,NULL,thread_fun1,(void*)message);//create thread1

 16       if(lv==0)

 17       {

  printf("thread 1 is created\n");

 19       }

 20       pthread_join(tid1,&retval);

 21       printf("retval=%s\n",(char*)retval);

 22

 23       message="THIS IS WINDOWS";

 24         lv=pthread_create(&tid2,NULL,thread_fun2,(void*)message);

 25       if(lv==0)

 26       {

 27           printf("thread 2 is created\n");

 28       }

 29       pthread_join(tid2,&retval);//will wait untill thread 1 function executes

 30       printf("retval=%s\n",(char*)retval);//returned value is printed by typecasting

 31       message="THIS IS 8051";

 32         lv=pthread_create(&tid3,NULL,thread_fun3,(void*)message);

 33       if(lv==0)

 34       {36       }

 37       pthread_join(tid3,&retval);//all pthread_join function will wait diffrently fo    r their return code...whenever they get their finished thread return code..main thre    ad will execute next instruction

 38       printf("retval=%s\n",(char*)retval);

 39       message="THIS IS MAC";

 40         lv=pthread_create(&tid4,NULL,thread_fun4,(void*)message);

 41       if(lv==0)

 42       {

 43           printf("thread 4 is created\n");

 44       }

 45       pthread_join(tid4,&retval);

 46       printf("retval=%s\n",(char*)retval);

 47       return 0;

 48     }

 49 void* thread_fun1(void* arg)//each & every function will execute in synchronized man    nner by using pthread_join....thread1 then thread2 ..so on //main thread will  wait     by using pthread_join for every thread to finish in synchronised & parallel manner

50 {

 51     int a,b=2;

 52       a=++b;

 53     printf("arg=%s\n",(char*)arg);

 54     printf("...whose priority is %d\n",a);

 55     pthread_exit("LINUX");

 56 }