consider the following c program
main()
{
fork();
fork();
printf("hello!\n");
}
为什么会print出4个'hello!'?
{
fork();
fork();
printf("hello!\n");
}
为什么会print出4个'hello!'?
consider the following c program
谢谢!
是不是这样
读到第一个fork(),program另外copy多一个fork();printf()
so far, you have 1 parent program and exact same child program with the content---- fork(); printf();
each of them read upto second fork() will produce two children programs again, with the content---printf();
It's like a tree.
1
^
1 1
^ ^
11 11
After I tried this simply program in unix, i get the answer
4
so far, you have 1 parent program and exact same child program with the content---- fork(); printf();
each of them read upto second fork() will produce two children programs again, with the content---printf();
It's like a tree.
1
^
1 1
^ ^
11 11
After I tried this simply program in unix, i get the answer
4
[A]BECAUSE YOU FORK() TWICE, YOU HAVE
FOUR PROCESSES RUNNING BEFORE PRINTF IS EXCUTED.
是不是这样读到第一个fork(),program另外copy多一个fork();printf()
so far, you have 1 parent program and exact same child program with the content---- fork(); printf();
each of them read upto second fork() will produce two children programs again, with the content---printf();
It's like a tree.
1
^
1 1
^ ^
11 11
After I tried this simply program in unix, i get the answer
4
updated
读到第一个fork(),program另外copy多一个fork();printf()
so far, you have 1 parent program and exact same child program with the content---- fork(); printf();
each of them read upto second fork() will produce two children programs again, with the content---printf();(by now you will have 4 printf("hello!")
After I tried this simply program in unix, i get the answer
4
It's like a tree.
f:fork p:printf
updated读到第一个fork(),program另外copy多一个fork();printf()
so far, you have 1 parent program and exact same child program with the content---- fork(); printf();
each of them read upto second fork() will produce two children programs again, with the content---printf();(by now you will have 4 printf("hello!")
After I tried this simply program in unix, i get the answer
4
It's like a tree.
f:fork p:printf
(more...)
[AGREE]EXACTLY.
pls refer to cs2106 lecture notes II.
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