3.Communication using pipes: Use pipes to rewrite part 4 in lab 05 to allow C1 t

Question

3.Communication using pipes:

Use pipes to rewrite part 4 in lab 05 to allow C1 to send the value for sum to C2 to use it in computing the average. Then C2 sends the value of average to C3 that uses it to compute the value of variance.

Code from part 4 of lab 5:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
int main(int argc, char ** argv)
{
   if (argc < 3)
   {
       printf("Usage : ./a.out num1 num2 ");
       return 0;
   }
   int i;
   int length = argc-1;
   float amount = (float)length;
   float mean=0;
   float average = 0;
   float sum = 0;
   float variance = 0;
   float difference = 0;
   float array[length];
   for(i = 1; i<=length;i++){ //create array filled with arguments from command line
      array[i-1] = atof(argv[i]);
   }
     
   if(fork() == 0) // create first child
   {
      for(i = 0;i<length;i++){ //calculate sum
        sum = sum + array[i];
      }
      printf("C1 sum - %.2f ",sum); //print sum
      exit(0); // exit with any value
   }
   else
   {
      wait(0);
      if(fork() == 0) // create second child
        {
          for(i = 0;i<length;i++){ //calculate sum
       sum = sum + array[i];
          }
          average = (float)sum/length; //calculate average
          printf("C2 average - %.2f ",average); //pring average
          exit(0); // exit
        }
      else
        {
          wait(0);
          if(fork() == 0) //create third child
              {
          for(i = 0;i<length;i++){ //calculate sum
            sum = sum + array[i];
          }
          average = (float)sum/length; //calculate average
          for(i = 0;i<length;i++){ //calculate variance
            difference = array[i]-average;
            variance = variance + (difference*difference);
          }
          printf("C3 variance - %.2f ", (float)variance/length); // print variance
          exit(0);
              }
          else
              {
          wait(0); // finally compilte after this wait
              }
        }
   }
}

Explanation / Answer

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
int main(int argc, char ** argv)
{
    if (argc < 3)
    {
        printf("Usage : ./a.out num1 num2 ");
        return 0;
    }
    int i;
    int length = argc-1;
    float amount = (float)length;
    float mean=0;
    float average = 0;
    float sum = 0;
    float variance = 0;
    float difference = 0;
    float array[length];
    for(i = 1; i<=length;i++){ //create array filled with arguments from command line
      array[i-1] = atof(argv[i]);
    }

   // create file descriptors
    int fd_pipe1[2]; // Used to store two ends of first pipe
    int fd_pipe2[2]; // Used to store two ends of second pipe

   // check if pipe connections are successful

   if ( -1 == pipe(fd_pipe1) )
    {
        fprintf(stderr, "Pipe creation failed" );
        return 1;
    }

    if ( -1 == pipe(fd_pipe2) )
    {
        fprintf(stderr, "Pipe creation failed" );
        return 1;
    }

    
    if(fork() == 0) // create first child
    {
      for(i = 0;i<length;i++){ //calculate sum
        sum = sum + array[i];
    }
      printf("C1 sum - %.2f ",sum); //print sum

   // close the reading end of pipe1 and write the Sum into it for reading by the other child.
        close(fd_pipe1[0]); // Close reading end of first pipe
        write(fd_pipe1[1], &sum, sizeof(sum)); // write sum into the pipe1
        close(fd_pipe1[1]); // close the writing end of pipe after placing the data

      exit(0); // exit with any value
    }
    else
    {
      wait(0);
      if(fork() == 0) // create second child
        {
       // close the wrintg end of pipe1 and read the Sum from the same pipe.
        close(fd_pipe1[1]); // Close wrintg end of first pipe
        read(fd_pipe1[0], &sum, sizeof(sum)); // read sum from the pipe1
        close(fd_pipe1[0]); // close the reading end of pipe after fetching the data
                  
          average = (float)sum/length; //calculate average
          printf("C2 average - %.2f ",average); //pring average
      
       // close the reading end of pipe2 and write the average into it for reading by the other child.
        close(fd_pipe2[0]); // Close reading end of first pipe
        write(fd_pipe2[1], &average, sizeof(average)); // write average into pipe2
        close(fd_pipe2[1]); // close the writing end of pipe after placing the data
      
          exit(0); // exit
        }
      else
        {
          wait(0);
          if(fork() == 0) //create third child
          {
          
       // close the wrintg end of pipe2 and read the average from the same pipe.
        close(fd_pipe2[1]); // Close wrintg end of second pipe
        read(fd_pipe2[0], &average, sizeof(average)); // read average from the pipe2
        close(fd_pipe2[0]); // close the reading end of pipe after fetching the data
      
          for(i = 0;i<length;i++){ //calculate variance
            difference = array[i]-average;
            variance = variance + (difference*difference);
          }
          printf("C3 variance - %.2f ", (float)variance/length); // print variance
          exit(0);
               }
          else
               {
          wait(0); // finally compilte after this wait
               }
        }
    }
}

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.