CODEWITHSUNDEEP
cprocesspipefork
KolteStar371
KolteStar371

Reputation: 69

Passing an array of integers from process within pipes

I've to solve a problem in C. I've two process, P1 and P2. P1 takes an array of integers and have to send it to P2, P2 have to check only prime numbers in this array, modify it and send back to P1, P1 have to print the modified array.

Example: Array of Int (myArr) = {3,9,17,21,4,2,5} Final result = {3,0,17,0,0,2,5}

The problem is, how can I send the array of integers trough pipes?

 //parent process
  if(p>0)
   {
    int i;
    int printArr[N];

    close(fd1[0]);
   //myArr is an array of integers previously declared
    write(fd1[1],myArr,N);


    close(fd1[1]);


    wait(NULL);

    close(fd2[1]);
    read(fd2[0],printArr,N);

    printf("\nPrinting modified array: ");
    for(i=0; i<N; i++)
    {
        printf("\t%d",printArr[i]);
    }

    close(fd2[0]);


}

 //child process
 else if(p==0)
   {
    int i,k;
    close(fd1[1]);
    int readArr[N];

    read(fd1[0],readArr,N);

            //here's the problem, it doesn't print correct values
    printf("Array that comes from parent");
    for(i=0; i<N; i++)
    {
        printf("\n%d\n",readArr[i]);
    }


    for(i=0; i<N; i++)
    {
        k=checkprime(readArr[i]);
        if(k==1)
            readArr[i]=0;
    }

    close(fd1[0]);
    close(fd2[0]);

    write(fd2[1],readArr,sizeof(readArr)+1);
    close(fd2[1]);

    exit(0);
      }

As I commented my code, when I read the array from pipe into readArr, it doesn't print correctly.

Upvotes: 0

Views: 245

Answers (1)

Iguananaut
Iguananaut

Reputation: 23356

Your read() call is reading N bytes into an array of N ints. Use read(fd, buf, N * sizeof(int)). Looks like you need to fix write() as well.

Upvotes: 2

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