Question

please use linux or unix to complete, and include pictures of the output.

Modify the code below to implement the program that will sum up 1000 numbers using 5 threads.

1st thread will sum up numbers from 1-200

2nd thread will sum up numbers from 201 - 400

...

5th thread will sum up numbers from 801 - 1000

Make main thread wait for other threads to finish execution and sum up all the results.

Display the total to the user.

#include <pthread.h>

#include <stdio.h>

#include <stdlib.h>

#define N_OF_THREADS 4
void * print(void *tid){

printf("Hello %d\n", tid); pthread_exit(NULL);
}
int main(){

pthread_t threads[N_OF_THREADS];

int status, i; //

printf("Main. Creating thread %d\n", i);

for (int i=0; i<N_OF_THREADS; i++) {    

printf("Main. Creating thread %d\n", i);

status = pthread_create(&threads[i], NULL, print, (void*)i);

if(status){

printf("Error %d\n", status);

exit(-1);

}

}

exit(NULL);

}

Answer 1

Look at my code and in case of indentation issues check the screenshots.

---------main.c---------------

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>

#define N_OF_THREADS 5

struct range{   //create a structure to pass as parameter to the thread
   int tid;   //The structure contains thread id, the and the range of numbers to compute sum
   int start;
   int end;
};

int sum_values[N_OF_THREADS] = {0};   //create sum array with all values as 0, each thread will write its output to sum array at thread index

void *computeSum(void *param)
{
   struct range *ptr = (struct range *) param;   //get the structure parameter as pointer
   int i;
   for(i = ptr->start; i <= ptr->end; i++)       //compute the sum from start to end
       sum_values[ptr->tid] = sum_values[ptr->tid] + i;   //update the sum array at the thread index

   //print threaad output
   printf("\nThread %d computed sum from %d to %d, SUM = %d", ptr->tid, ptr->start, ptr->end, sum_values[ptr->tid]);
   pthread_exit(NULL);
}

int main()
{
   pthread_t threads[N_OF_THREADS];   //create thread ids as array

   int status, i;   //
   for (i = 0; i < N_OF_THREADS; i++)   //loop for number of threads
   {
       printf("\nMain. Creating thread %d", i);
       struct range *r = malloc(sizeof(struct range));   //create a structure object pointer
       r->tid = i;                       //update the thread id
       if(i == 0){                       //update the range for according to the thread id
           r->start = 1;
           r->end = 200;
       }  
       else if(i == 1){
           r->start = 201;
           r->end = 400;
       }  
       else if(i == 2){
           r->start = 401;
           r->end = 600;
       }  
       else if(i == 3){
           r->start = 601;
           r->end = 800;
       }  
       else if(i == 4){
           r->start = 801;
           r->end = 1000;
       }  
       status = pthread_create(&threads[i], NULL, computeSum, r); //start the thread, pass structure parameter
       if(status){
           printf("Error %d\n", status);
           exit(-1);
       }
   }
  
   for (i = 0; i < N_OF_THREADS; i++){
       pthread_join(threads[i], NULL);   //main waits for all the threads to exit
   }

   int total = 0;
   for (i = 0; i < N_OF_THREADS; i++){
       total = total + sum_values[i];   //main adds the sum of the values computed by the threads
   }  
   printf("\n\nThe sum of numbers from 1 to 1000 is %d\n", total); //print total
   exit(0);
}

----------Screenshots--------------

----------Output--------------

---------Updated answer-------------------------

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