Finding the level of a child process in a process tree - c

Question

I've been trying to create a process tree using fork() and print each child's level (0 for base process, 1 for its child, 2 for its grandchild etc.) in the tree. The code below only works for depth 0 and 1. Any idea how I can improve it?
Thanks.
#include <stdio.h>
#include <unistd.h>
int i;
int main()
{
pid_t baseID = getpid();
printf("Base Process ID: %d, level: 0 \n", baseID);
for (i = 0; i < 3; i++) {
int level = 1;
pid_t pid;
pid = fork();
if (pid == 0) {
pid_t childID = getpid();
pid_t parentID = getppid();
if (parentID == baseID) {
level = 1;
}
else {
// do something for grandchildren here
level++;
}
printf("Process ID: %d, Parent ID: %d, level: %d \n", getpid(), getppid(), level);
}
else {
wait(NULL);
}
}
return 0;
}

Answer 1

The intended process tree is the following:
0
|->1
| |->2
| | |->3
| |
| |->2
|
|->1
| |->2
|
|->1
So to be able to print the level of each process, we should just initialize the level variable to 0 outside the main for loop and just increment its value each time a child process is created.
The following code will print the level of each child process as expected:
#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
int main()
{
pid_t baseID = getpid();
printf("Base Process ID: %d, level: 0 \n", baseID);
int level = 0;
for (int i = 0; i < 3; i++) {
pid_t pid = fork();
if (pid == 0) { // Child
pid_t childID = getpid();
pid_t parentID = getppid();
level++;
printf("Process ID: %d, Parent ID: %d, level: %d \n", getpid(), getppid(), level);
} else { // Parent
wait(NULL);
}
}
return 0;
}