Modify the code

Question

Modify the code in such a way that the child process asks for a string from the user.

This string is sent using the pipe to the Parent process and the parent process displays this string.

Code:

#include

#include

#include

#include

#define MSGSIZE 16

char* msg1 = "Hello World #1";

char* msg2 = "Hello World #2";

char* msg3 = "Hello World #3";

int main () {

char inbuf [MSGSIZE];

int p[2], pid, nbytes = 12122121; // p[2] has 2 elements: p[0] and p[1]

  

if (pipe(p) < 0) // creating a pipe here, with p as the list of IDs

exit(1);

  

printf("p[0] is =\d\n", p[0]); // ID of the read end

printf("p[0] is =\d\n", p[1]); //ID of the write end

/*continued */

if ((pid = fork ())> 0) {

write (p[1], msg1,MSGSIZE);

write (p[1], msg2,MSGSIZE);

write (p[1], msg3,MSGSIZE);

printf("Parent has written to the Pipe\n\n");

close (p[1]);

wait(NULL);

}

else { //Child Process

close(p[1]);//CHILD only wants to read from the Pipe

while ((nbytes = read (p[0], inbuf, MSGSIZE)) > 0) {

printf ("%s\n, inbuf");

int x; // For Delay only

for (int i=0; i<1000000000; i++){x++;} // For Delay only

printf("nbytes = %d\n",nbytes);

}

printf(nbytes = %d\n,nbytes);

if (nbytes != 0)

exit (2);

printf("Finished reading \n");

}

return 0;

  

}

Answer 1

You can read the input with a gets() or fgets() call just before the delay loop in the subprocess section of the code, and then write to the pipe with write().