confusing fork system call
- by benjamin button
Hi,
i was just checking the behaviour of fork system call and i found it very confusing.
i saw in a website that
Unix will make an exact copy of the parent's address space and give it to the child. Therefore, the parent and child processes have separate address spaces
#include <stdio.h>
#include <sys/types.h>
int main(void)
{
pid_t pid;
char y='Y';
char *ptr;
ptr=&y;
pid = fork();
if (pid == 0)
{
y='Z';
printf(" *** Child process ***\n");
printf(" Address is %p\n",ptr);
printf(" char value is %c\n",y);
sleep(5);
}
else
{
sleep(5);
printf("\n ***parent process ***\n",&y);
printf(" Address is %p\n",ptr);
printf(" char value is %c\n",y);
}
}
the output of the above program is :
*** Child process ***
Address is 69002894
char value is Z
***parent process ***
Address is 69002894
char value is Y
so from the above mentioned statement it seems that child and parent have separet address spaces.this is the reason why char value is printed separately and why am i seeing the address of the variable as same in both child and parent processes.?
Please help me understand this!
