CS1411 Exercise – 11 – Threading Applications solution


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1. Write a multithreaded program that calculates various statistical values for a list of

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

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

Main thread creates a thread to find the summation of given ‘n’
#include < pthread.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 \n”);
return -1;
if (atoi(argv[1]) < 0) { fprintf(stderr,”%d must be >= 0 \n”,atoi(argv[1]));
return -1;
/* get the default attributes */

/* create the thread */
/* wait for the thread to exit */
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;