关于C和UNIX（MORE QUESTION）1)在CS2281的TEST2中，有这样一个问题：
How many lines are printed by the following program?
main(){
if(fork()||fork()&&fork())
printf("%d\n", getpid());
}
答案是2。
哪位高手能指教一下为什么是2吗？
我在UNIX下分别试验了
main(){
if(fork()||fork())
printf("%d\n", getpid());
}
/*print 2 lines*/
------------------------------
main(){
if(fork()&&fork())
printf("%d\n", getpid());
}
/*print 1 lines*/
------------------------------
main(){
if(fork()&&fork()&&fork())
printf("%d\n", getpid());
}
/*print 1 lines*/
------------------------------
main(){
if(fork()||fork()||fork())
printf("%d\n", getpid());
}
/*print 3 lines*/
我是只知其然，不知其所以然。如果哪位兄台能解惑一二，在下真的很感激，无论最后拿A还是拿D。
2）还有一题：
What output valus are possible by the following program?
main(){
if(!fork())
printf("%d\n", getpid())
}
(A)>1 (B) >=1 (C)2 (D)3 (E)NONE OF THE ABOVE
答案是B，可我认为是A。
这个一定是个CHILD PROCESS，� (more...)
>>
1.
The parent process P creates a child process P1, then print a line. The return value of the (1st) fock() for process P1 is 0,
so the second part of OR (||) is executed. As a result, P1 creates a new process P2. For P1, (fork()||fork()) is true, so the second part of AND(&&) should be executed: a new process P3 is created. For p1 the if condition is true, so p1 prints a line. For p2, fork()||fork() is false, so the if condition is false(note the 3rd fork() will not be executed), p2 doesn't execute printf statement. For p3, the 3rd fork() return 0, so the if condition is false. It skips printf statement. please correct me if i am wrong.
2.
I also choose A. PID 1 : init, is the parent process of all other processes in unix.
4.
For root directory, both . and .. refer to itself. so they have the same inode number. Note the parent of root is itself.
If i am wrong, Please correct me
The parent process P creates a child process P1, then print a line. The return value of the (1st) fock() for process P1 is 0,
so the second part of OR (||) is executed. As a result, P1 creates a new process P2. For P1, (fork()||fork()) is true, so the second part of AND(&&) should be executed: a new process P3 is created. For p1 the if condition is true, so p1 prints a line. For p2, fork()||fork() is false, so the if condition is false(note the 3rd fork() will not be executed), p2 doesn't execute printf statement. For p3, the 3rd fork() return 0, so the if condition is false. It skips printf statement. please correct me if i am wrong.
2.
I also choose A. PID 1 : init, is the parent process of all other processes in unix.
4.
For root directory, both . and .. refer to itself. so they have the same inode number. Note the parent of root is itself.
If i am wrong, Please correct me
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