how fork works with logical operators

问题:

main()
{
    if (fork() || (fork() && fork()))
    printf("AA\n");
    else if (!fork())
    printf("BB\n");
    else
    printf("CC\n");
}

I have run the following code and get the results AA AA CC BB CC BB. While I understand how fork works, I don't understand what it does with logical operators. The teacher in our class wants us to give the answers for this homework. While I can easily run this program, I would like to know what happens exactly. Can anyone explain or direct me to a website to what happens when using fork with logical operators.

I am pretty new to c/c++ so go easy on me. Thanks

回答1:

fork() returns 0 (false) to the child process, and non-zero (true) to the parent process.

You can apply logical operators to these booleans.

Remember that logical operators will short-circuit, so 0 || fork() will not call fork at all.

If you read carefully through the code and think about what each fork() call will return, you should be able to figure it out.