Help!

[LiamSalt]

Sorry I know this is a C++ forum but I am hoping there is someone that can help me!

I am new to coding in C and even newer to using VIM

I am currently trying to write a code that will store PID numbers of a child after a fork, I have to be able to enter an amount that will be created, so far I have managed to be able to get them to print (which puts me on the right path as far as I am concerned) but I am having issues.

Using the following code:

1 #include <stdio.h>
2 #include <sys/types.h>
3 #include <unistd.h>
4 #include <stdlib.h>
5
7 int main(int argc, char *argv[])
8 {
9 int prod = atoi(argv[1]);
10 int count = 0;
11
12 if(argc == 2)
13 {
14 while(count < prod)
15 {
16 printf("success\n\n");
18 int i;
19 i=fork();
20 printf("\n");
21
22 if(i==0)
23 {
24 printf("Child printing");
25 printf("getpid: %d, getppid: %d
\n",getpid(), getppid());
26 }
27
28 count++;
29 }
30
31 }
32 else
33 {
34 printf("Not enough paramterers");
35 }
36
37 return 0;
38
39 exit(0);
40 }

while this has some success, it is for some reason creating a 3rd iteration and I can't work out why

The "success" print is more of a marker, but every time I run the program I get this result:

k110-1:~ s029119a$ ./try3.exe 2
success


success



Child printinggetpid: 9335, getppid: 1
success


k110-1:~ s029119a$
Child printinggetpid: 9336, getppid: 1

Child printinggetpid: 9337, getppid: 1

Can anyone offer any advice or tell me what I'm doing wrong, why is it doing this?

[GCDEF]

Help us help you by posting properly indented code between code tags, and without line numbers.

[LiamSalt]

Code:

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

int main(int argc, char *argv[])
{
int prod = atoi(argv[1]);
int count = 0;

if(argc == 2)
{
while(count < prod)
{
printf("success\n\n");
int i;
i=fork();
printf("\n");

if(i==0)
{
printf("Child printing");
printf("getpid: %d, getppid: %d \n",getpid(), getppid());
}
count++;
}
}
else
{
printf("Not enough paramterers");
}

return 0;

exit(0);
}

Result:

k110-1:~ s029119a$ ./try3.exe 2
success


success



Child printinggetpid: 9484, getppid: 1
success



Child printinggetpid: 9485, getppid: 1
k110-1:~ s029119a$
Child printinggetpid: 9486, getppid: 1

Hows that?

[2kaud]

When posting code, Go advanced, select code and then click '#'

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

int main(int argc, char *argv[])
{
int prod = atoi(argv[1]);
int count = 0;

	if (argc == 2) {
		while (count < prod) {
			printf("success\n\n");
			int i;
			i = fork();
			printf("\n");

			if (i == 0) {
				printf("Child printing");
				printf("getpid: %d, getppid: %d\n",getpid(), getppid());
			}
			count++;
		}
	} else {
		printf("Not enough paramterers");
	}
	return 0;
}

[GCDEF]

When posting code, Go advanced, select code and then click '#'

Wouldn't it be better to let the poster do it himself that to do it for him? FWIW, I find that formatting style just about as unreadable as the original.

[LiamSalt]

Code:

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

int main(int argc, char *argv[])
{
   int prod = atoi(argv[1]);
   int count = 0;
 
   if(argc == 2)
   {
      while(count < prod)
   {
   printf("success\n\n");
   int i;
   i=fork();
   printf("\n");
 
   if(i==0)
   {
      printf("Child printing");
      printf("getpid: %d, getppid: %d \n",getpid(), getppid());
   }

   count++;
   }

   }
   else
   {
      printf("Not enough paramterers");
   }
 
   return 0;

exit(0);
}

Result:

k110-1:~ s029119a$ ./try3.exe 2
success


success



Child printinggetpid: 9335, getppid: 1
success


k110-1:~ s029119a$
Child printinggetpid: 9336, getppid: 1

Child printinggetpid: 9337, getppid: 1

[LiamSalt]

Okay done, do you have any suggestions as for my issue?

[VictorN]

Okay done, do you have any suggestions as for my issue?

please, indent your code properly!

[VictorN]

Okay done, do you have any suggestions as for my issue?

Well, one very important suggestion is you must use debugger!

[LiamSalt]

I'm using VIM, it's a shell, I don't know how to use it.

I was wondering if it was something to do with the getpid() function as it prints 2 on the second iteration?

[LiamSalt]

Appreciate the help but I've worked it out, I wasn't returning 0 in the it statement that gets and prints the child pid

[2kaud]

I'm got no experience of fork as Windows doesn't support this. However, you might get some info from here

http://mij.oltrelinux.com/devel/unixprg/#tasks