Does if(fork()) create a child process? [closed]

Answer 1

The answer is

if (fork ())

may or may determine whether a child process was created.

Go to the man page:

http://man7.org/linux/man-pages/man2/fork.2.html

We find that fork () returns three types of values:

• -1 => fork() failed
• 0 => return value in the child process
• a positive value => success and the PID of the child process.

Thus the test

if (fork ()) 

which is the same as

if (fork () != 0)

may succeed whether or not a child process was created. A competently written question would have said

if (fork () > 0)

Assuming everything works correctly:

int main() 
{
    int v=0;

    if(fork())  // Creates a child process that does nothing.
    {
        v++;

       if(!fork()) // Creates a child process that creates a child process (that then does nothing but decrement v).
       {
           fork();
          v--; 
       }
   }  
}