reverse calls order in fork - linux

Question

Warm greetings,
I wrote these lines which display 4 messages corresponding to 'A', 'B', 'C', and 'D' with a for loop and fork. I would like to reverse the calls (output becomes 'D' 'C' 'B' 'A') by making the parent process wait for the children to execute first.
Initial code (right order from A to D):
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
int main(){
int i;
for(i=0;i<4;i++){
if (fork()){
break;
}
printf("Mon nom est %c. Je viens du processus %d\n",'A'+i,getpid());
}
return(0);
}
My code for the desired output (from D to A):
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
int main(){
int i;
for(i=0;i<4;i++){
if (fork()){
wait(NULL);
break;
}
printf("Mon nom est %c. Je viens du processus %d\n",'A'+i,getpid());
}
return(0);
}
I added wait(NULL) but it doesn't seem to help.
I thank you all in advance!!

Answer 1

Lets trace i between the processes:
P0:i=0; fork(); wait(); exit();
P1: i=0; printf(); i = 1; fork(); wait(); exit();
P2: i=1; printf(); i=2; fork(); wait(); exit();
See the pattern; the parent is always wait()ing and exit()ing without printing. The child prints in the parents place, then becomes the parent of the next generation.
Not to be too picky about style, but even such a small program can benefit from a structured indentation:
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
int main() {
int i;
for (i=0;i<4;i++) {
if (fork()) {
wait(NULL);
break;
}
printf("Mon nom est %c. Je viens du processus %d\n",'A'+i,getpid());
}
return(0);
}