Question

4. 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 five separate worker threads. One thread will determine the average of the numbers, the second will determine the maximum value, the third will determine the minimum value, fourth will determine the median value and the fifth will compute the std. deviation.

For example, suppose your program is passed the integers 90 81 78 95 79 72 85

The program will report

The average value is 82.8

The minimum value is 72

The maximum value is 95

The median value is 81

The standard deviation is 7.2

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.

Answer 1

Code:

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
 
void *avg_func(void *str);
void *min_func(void *ptr);
void *max_func(void *ptr);

double avg;        
int min;
int max;

typedef struct datastruct
{
    int size;
    int * values;
}datastruct;

main(int argc, char *argv[])
{
        printf("\n\nWelcome to paheeThredz, by Sean Staz\n\n");
    while(argc <=1)
    {
        printf("Incorrect input. No arguments entered.\n");
        printf("Please enter one or more inputs.\n");
        exit(0);
        }
    
    int i = 0;
    int copy[argc-1];
    for(i; i < (argc -1); i++)
    {
        copy[i] = atoi(argv[i+1]);
    }
        
    pthread_t thread1, thread2, thread3;
    const char *message1 = "This is Thread 1";
    const char *message2 = "This is Thread 2";
    const char *message3 = "This is Thread 3";
    int  t1, t2, t3;
 
    printf("Running: %s\n\n", argv[0]);
    
    datastruct ds = {argc - 1, copy};
 
    t1 = pthread_create(&thread1, NULL, (void *) avg_func, (void *) &ds);
    if(t1)
    {
        fprintf(stderr,"Error - pthread_create() return code: %d\n", t1);
        exit(EXIT_FAILURE);
    }
 
    t2 = pthread_create(&thread2, NULL, (void *) min_func, (void *) &ds);
    if(t2)
    {
        fprintf(stderr,"Error - pthread_create() return code: %d\n",t2);
        exit(EXIT_FAILURE);
    }
     
    t3 = pthread_create(&thread3, NULL, (void *) max_func, (void *) &ds);
    if(t3)
    {
        fprintf(stderr,"Error - pthread_create() return code: %d\n", t3);
        exit(EXIT_FAILURE);
    }
 
    printf("pthread_create() for Thread 1 returns: %d\n",t1);
    printf("pthread_create() for Thread 2 returns: %d\n",t2);
    printf("pthread_create() for Thread 3 returns: %d\n\n",t3);
 
 
    pthread_join(thread1, NULL);
    pthread_join(thread2, NULL);
    pthread_join(thread3, NULL);
 
    printf("The average:  %g\n", avg);
    printf("The minimum:  %d\n", min);
    printf("The maximum:  %d\n", max);
 
    exit(EXIT_SUCCESS);
}
 
void *avg_func(void *ptr)
{
    datastruct * copy;
    copy = (datastruct *) ptr;
    
    int sz = copy->size;
    int i;
    
    for(i = 0; i < sz; i++)
    {
        avg += (copy->values[i]);    
    }                               
    avg = (int)(avg / sz);          
}

void *min_func(void *ptr)
{
    datastruct * copy;
    copy = (datastruct *) ptr;
    
    int sz = copy->size;
    int i;
    
    min = (copy->values[0]);
    for(i = 1; i < sz; i++)
    {
        if(min > (copy->values[i]))
        {
            min = (copy->values[i]);
        }
    }
}

void *max_func(void *ptr)
{
    datastruct * copy;
    copy = (datastruct *) ptr;
    
    int sz = copy->size;
    int i;
    
    max = copy->values[0];
    
    for(i = 1; i < sz; i++)
    {
        if(max < copy->values[i])
        {
            max = copy->values[i];
        }
    }
}

Let me know if you have any doubts or if you need anything to change. 

If you are satisfied with the solution, please leave a +ve feedback : ) Let me know for any help with any other questions.

Thank You!
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