UCS1411-Lab 13 Threading Applications Solved

1. Write a multithreaded program that calculates various statistical values for a list of numbers. This program will be passed a series of numbers on the command line and will then create three separate worker threads. One thread will determine the average of the numbers, the second will determine the maximum value, and the third will determine the minimum value. For example, suppose your program is passed the integers

 

                                  90 81 78 95 79 72 85

 

           The program will report

                       The average value is 82

                       The minimum value is 72

                       The maximum value is 95

             

 The variables representing the average, minimum, and maximum values will be stored globally. The worker threads will  set these values, and the parent thread will output the values once the workers have exited. (We could obviously expand  this program by creating additional threads that determine other statistical values, such as median and standard deviation.)

 

 

Example:

  Main thread creates a thread to find the summation of given ‘n’ 

 

#include < pthread.h #include <stdio.h

int sum; /* this data is shared by the thread(s) */ void *runner(void *param); /* threads call this function */ int main(int argc, char *argv[])

{ pthread_t tid; /* the thread identifier */ pthread_attr_t attr; /* set of thread attributes */ if (argc != 2)

{ fprintf(stderr,"usage: a.out <integer value\n"); return -1; }

if (atoi(argv[1]) < 0)

{

fprintf(stderr,"%d must be = 0 \n",atoi(argv[1]));

return -1;

}

/* get the default attributes */ pthread_attr_init(&attr); /* create the thread */

pthread_create(&tid,&attr,runner,argv[1]); /* wait for the thread to exit */ pthread_join(tid,NULL); printf("sum = %d\n",sum);

}

/* The thread will begin control in this function */

void *runner(void *param)

{ int i, upper = atoi(param); sum = 0; for (i = 1; i <= upper; i++) sum += i; pthread_exit(0);

}