Thread: have I got forking problems, or what?

lads

I'm new to C, and am playing catch-up on assignments. While I'm not looking for anyone to do work for me, I nevertheless need someone to walk me through a problem. I understand forking, but my problem is the structure of the program itself. What I basically need to know is how to deal with all the child PIDs first (i.e. printf "I'm a kid and my pid is: ) but 'remember' those PIDs so that the parent can report/list them before it dies. A pitiful problem I admit.

Please help.

Ok, maybe if I'm a bit more specific.

This is me at the moment

Code:

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

typedef enum boolean { BFALSE, BTRUE } bool_t;

static bool_t valid_data ( int n, char *s )
{
  if ( strlen ( s ) != 2 || n < 1 || n > 9 )
    return BFALSE;

  return BTRUE;
}
int main ( void )
{
  int num;
  int i;
  int p;

  printf ( "Enter an number between 1 and 9: " );

  if ( scanf ( "%d", &num ) != 1 )
    die ( "Invalid input" );
    
  if ( valid_data ( n, s ) != BFALSE )
  while (num <= o);
  
  
#     I'm happy that my fork code goes here, but without creating #multiple buffers, how do I manage this so 
# that all the children printf "CHILD: pid" on a seperate line, followed by the parent 
#printing that they are the parent, while mentioning each child? #e.g.
#Output if user called program and 3
#CHILD: 1
#CHILD: 2
#CHILD: 3
#PARENT: I am 0 and my child is 1
#PARENT: I am 0 and my child is 2
#PARENT: I am 0 and my child is 3

  else
    die ( "Invalid input" );

  return EXIT_SUCCESS;
}

lol, was tyoing and posting when you sent your reply, but my problem isn't forking, its fecking basic structure <sigh> forking hell

lol

Thanks for at least one person picking up on the forking reference though. nice to see someone with a sense of humour, and possessed of C.

Code:

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>


int main( int argc , char** argv ){
   int count = 0 ;
   int status = -1 ; /* Status for wait() */
   pid_t pid ; /* pid of child process */
   pid_t my_pid = getpid(); /* get current pid */

   if( sscanf( argv[1] , "%d" , &count ) == 0){
      fprintf( stderr , "Error reading int from parameter\n");
      return EXIT_FAILURE ;
   }

   if( count > 10 || count < 0 ){
      fprintf( stderr , "Error, number not in range 0-9. \n");
      return EXIT_FAILURE ;
   }

   /* Create 'count' number of processes */
   while( count-- > 0 ){
      pid = fork();
      
      if( pid == 0 ){
      /* In child, so report, and break so not to fork() */
         my_pid = getpid();
         printf("CHILD: %d\n", my_pid);
         break ; 
      }
   }
   
   /* Keep looping untill evey child process had terminated */
   while (pid != -1 ){
      pid = wait(&status);
      if( pid != -1 )
         printf("PARENT: I am %d. The child is %d\n", my_pid, pid);
   }

   return EXIT_SUCCESS ;
}

ok, last question, anyone, what line do I add to the above code to make sure that all PID's are killed off?

Agreed, if I could post the assignment, I would, but basically the dutch C lecturer enjoys playing games. Though he threw us a bone with the sscanf, he played down (heavily) the use of the wait () command here. I hate what I have done, but it meets and exceeds spec.

I'll just go wash my hands now...