Hi all,
I am stuck with this code..Can anyone tell me how to implement semaphores in
fork system call
Code:
#include<stdio.h>
int signal(int *n);
int wait(int *n);
int main()
{
int n;
n=0;
if(fork())
{
printf("Hello");
signal(&n);
}
else
{
wait(&n);
printf("World");
}
}
int signal(int *n)
{
(*n)++;
}
int wait(int *n)
{
while((*n)<=0);
(*n)--;
}
Since parent process and child process will be having different address
spaces...so change of n in one address space will not be visible to other.so
please tell me how to make n visible to both the processes
On Fri, Jun 3, 2011 at 2:45 PM, Subhransu <[email protected]>wrote:
> Here you go in C code
> http://codepad.org/gk6AZj0T
>
>
> int main()
> {
> if(printf("hello")!=0) {
> printf("world");
> }
> else {
> printf("SCREWED ! ! !"); }
>
> return 0;
> }
>
> *
> *
>
> *
> *
>
> *Subhransu Panigrahi
> *
> *Mobile:* *+91-9840931538*
> *Email:* [email protected]
>
>
>
> On Fri, Jun 3, 2011 at 1:57 PM, Naveen Kumar
> <[email protected]>wrote:
>
>> Hi Shachindra,
>> I don't think letters will be jumbled because we a calling one api to
>> output on console & tty's driver takes whole line and output it at once.
>>
>> On Fri, Jun 3, 2011 at 12:40 PM, Vishal Thanki <[email protected]>wrote:
>>
>>> @sachindra, @naveen,
>>> this was just a plain trick to execute "if" and "else" block. i agree
>>> with your concerns :)
>>>
>>> 2011/6/3 Vιиodh <[email protected]>:
>>> > @vishal:
>>> > can u explain the fork() solution??
>>> >
>>> > On Fri, Jun 3, 2011 at 12:16 PM, Shachindra A C <[email protected]
>>> >
>>> > wrote:
>>> >>
>>> >> There can be some synchronisation problems with fork() right? say
>>> world
>>> >> might get printed first...or maybe the letters can get jumbled
>>> too...We
>>> >> cannot guarantee the order of execution unless we use semaphores.
>>> >>
>>> >> On Fri, Jun 3, 2011 at 12:14 PM, Naveen Kumar <
>>> [email protected]>
>>> >> wrote:
>>> >>>
>>> >>> oh yes,
>>> >>> gud one
>>> >>>
>>> >>> On Fri, Jun 3, 2011 at 12:12 PM, Vishal Thanki <
>>> [email protected]>
>>> >>> wrote:
>>> >>>>
>>> >>>> vishal@ubuntu:~/progs/c\ 12:11:53 PM >$ cat fork.c
>>> >>>> #include <stdio.h>
>>> >>>> #include <stdlib.h>
>>> >>>>
>>> >>>> int main()
>>> >>>> {
>>> >>>> if (fork()) {
>>> >>>> printf("hello ");
>>> >>>> } else {
>>> >>>> printf("world\n");
>>> >>>> }
>>> >>>> return 0;
>>> >>>> }
>>> >>>> vishal@ubuntu:~/progs/c\ 12:11:56 PM >$ gcc fork.c
>>> >>>> vishal@ubuntu:~/progs/c\ 12:12:06 PM >$ ./a.out
>>> >>>> hello world
>>> >>>>
>>> >>>>
>>> >>>> On Fri, Jun 3, 2011 at 12:09 PM, Naveen Kumar
>>> >>>> <[email protected]> wrote:
>>> >>>> > Hi Vishal,
>>> >>>> >
>>> >>>> > Can you show us how it be done with fork?
>>> >>>> >
>>> >>>> > On Fri, Jun 3, 2011 at 12:02 PM, Vishal Thanki
>>> >>>> > <[email protected]>
>>> >>>> > wrote:
>>> >>>> >>
>>> >>>> >> can use fork() also..
>>> >>>> >>
>>> >>>> >> On Fri, Jun 3, 2011 at 11:57 AM, anand karthik
>>> >>>> >> <[email protected]> wrote:
>>> >>>> >> > (!printf("Hello"))
>>> >>>> >> >
>>> >>>> >> > On Jun 3, 2011 11:52 AM, "Arpit Mittal" <
>>> [email protected]>
>>> >>>> >> > wrote:
>>> >>>> >> >> Please help me in this question.
>>> >>>> >> >>
>>> >>>> >> >> What's the "condition" so that the following code prints both
>>> >>>> >> >> HelloWorld !
>>> >>>> >> >>
>>> >>>> >> >> if "condition"
>>> >>>> >> >> printf ("Hello");
>>> >>>> >> >> else
>>> >>>> >> >> printf("World");
>>> >>>> >> >>
>>> >>>> >> >>
>>> >>>> >> >>
>>> >>>> >> >>
>>> >>>> >> >> --
>>> >>>> >> >> -Arpit Mittal
>>> >>>> >> >> 6th Semester,
>>> >>>> >> >> Indian Institute of Information Technology,Allahabad
>>> >>>> >> >> Email : [email protected]
>>> >>>> >> >> [email protected]
>>> >>>> >> >> Contact : +91-8853049787
>>> >>>> >> >>
>>> >>>> >> >> Let every man be respected as an individual and no man
>>> idolized.
>>> >>>> >> >>
>>> >>>> >> >> --
>>> >>>> >> >> You received this message because you are subscribed to the
>>> Google
>>> >>>> >> >> Groups
>>> >>>> >> >> "Algorithm Geeks" group.
>>> >>>> >> >> To post to this group, send email to
>>> [email protected].
>>> >>>> >> >> To unsubscribe from this group, send email to
>>> >>>> >> >> [email protected].
>>> >>>> >> >> For more options, visit this group at
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>>> >>>> >> >>
>>> >>>> >> >
>>> >>>> >> > --
>>> >>>> >> > You received this message because you are subscribed to the
>>> Google
>>> >>>> >> > Groups
>>> >>>> >> > "Algorithm Geeks" group.
>>> >>>> >> > To post to this group, send email to
>>> [email protected].
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>>> >>>> >> >
>>> >>>> >>
>>> >>>> >> --
>>> >>>> >> You received this message because you are subscribed to the
>>> Google
>>> >>>> >> Groups
>>> >>>> >> "Algorithm Geeks" group.
>>> >>>> >> To post to this group, send email to [email protected].
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>>> >>>> >>
>>> >>>> >
>>> >>>> >
>>> >>>> >
>>> >>>> > --
>>> >>>> > Cheers
>>> >>>> > Naveen Kumar
>>> >>>> >
>>> >>>> > --
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>>> >>>> >
>>> >>>>
>>> >>>> --
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>>> >>>>
>>> >>>
>>> >>>
>>> >>>
>>> >>> --
>>> >>> Cheers
>>> >>> Naveen Kumar
>>> >>>
>>> >>> --
>>> >>> You received this message because you are subscribed to the Google
>>> Groups
>>> >>> "Algorithm Geeks" group.
>>> >>> To post to this group, send email to [email protected].
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>>> >>
>>> >>
>>> >>
>>> >> --
>>> >> Regards,
>>> >> Shachindra A C
>>> >>
>>> >> --
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>>> >
>>> >
>>> >
>>> > --
>>> > With regards,
>>> > Vιиodh
>>> >
>>> > --
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>>> >
>>>
>>> --
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>>>
>>
>>
>> --
>> Cheers
>> Naveen Kumar
>>
>> --
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>>
>
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--
Regards,
Nitish Goyal
Undergraduate Student Of NSIT,
Computer Engineering (B.E.)
Asst. PlaceComm 2011
contact me:- +91-9999605824
Reply at :- [email protected]
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