C#•4mo ago

if(fork) and if(!fork) - how do they work?

Let's say we have the following code:

pid_t pid;
pid = fork();
if(pid == 0) {
        if(fork()) printf("A");
        else printf("B");
        printf("C");
}
else {
        if(!fork()) printf("A");
        else if (fork()) printf("B");
        else printf("C");
}

pid_t pid;
pid = fork();
if(pid == 0) {
        if(fork()) printf("A");
        else printf("B");
        printf("C");
}
else {
        if(!fork()) printf("A");
        else if (fork()) printf("B");
        else printf("C");
}

How many A's, B's and C's are going to be printed? I'm a little bit confused with how fork() works inside "if" and whether I'm in parent or child process.

8 Replies

Pobiega•4mo ago

I think you are on the wrong discord my friend this is the C# discord. Your code is... C? C++? regardless, head to $cpp

MODiX•4mo ago

We're partnered with Together C & C++, check them out here: https://discord.gg/vnyVmAE

rho•4mo ago

wrong server.. im so sorry lol

Pobiega•4mo ago

no worries

rho•4mo ago

thanks for letting me know c:

Jimmacle•4mo ago

assuming c/c++, treating a number as a boolean is false if the number is 0 and true if the number is anything other than 0 so fork() in an if is just checking if the PID is nonzero dunno about inverting it with ! though, that looks weird and i wouldn't do it to begin with is that even valid?

rho•4mo ago

yeah it is

MutableString•4mo ago

when you fork() you spawn another process so in father process fork() will return false in child process it will return true (or reverse, i haven't used this stuff in years)

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if(fork) and if(!fork) - how do they work?