c - Why does this code using fork() work? -

i've code executes code depending of if active process parent or child process in infinite loop:

pid_t childpid;  childpid=fork();  while (1) {     if (childpid >=0)     {         if (childpid==0)         {             [do child process stuff]         }            else         {             [do parent process stuff]         }     }     else     {         printf("\n fork failed, quitting!!!!!\n");         return 1;        }  } 

code simple there's 1 big thing on me don't understand how happens although have guess:

if not taking consideration we're creating 2 processes looks childpid being reasigned don't think makes sense.

so guess, fork creates childpid each process, returning 0 parent process , pid child process, though syntax makes me think should return 1 result , assign chilpid.

is guess correct or there other thing involved?

thank you.

so guess, fork creates childpid each process, returning 0 parent process , pid child process, though syntax makes me think should return 1 result , assign chilpid.

exactly that. fork reference manual:

return value: on success, pid of child process returned in parent, , 0 returned in child. on failure, -1 returned in parent, no child process created, , errno set appropriately.

so

is guess

why guess if precisely defined in posix specification?