fork() function

Today I work on the fork function to create child process.I find some interesting things . But maybe not for u . Because I am a little bird!
The code :

//version 1.0

#include<sys/types.h>
#include<stdio.h>
#include<unistd.h>
int main(){
        pid_t pid,pid_1;
        printf("Starting ...\n");
        //let's parent process prints 'a'

        printf("a\n");
        //let't creat the first child process ,it will print 'b'

        pid = fork();
        if(pid == 0){
                printf("b\n");
        }
        //let't create the second child process ,it will print 'c'

        pid_1 = fork();
        if(pid_1 == 0){
                printf("c\n");
        }
        return 0;
}
//the output:

//Starting ...

//a

//b

//c

//c


//Analyze: This is the very simple version.The parent process print "a" first.
//Then it creates a child process and the child process print "b" . But after
//creating the second child process ,it prints two "c". To sovle this ,we must
//know the first point.When b process is created ,it continues running itself.
//Ok,the instruction "pid_1=fork()" is executed by process b. So the first "c" is printed.While the parent process is also runnning, it will also executed "pid_1=fork()" ,so the second "c" is printed. We can sovle the two "c" problem //now. But I find another interesting result that the "Starting..." is only printed once.When child process is created , it inherits the parent's resource include the runtime state ,but the child process has it own data segment.Let's see Version 1.1 to show this.

//Version 1.1

#include<sys/types.h>
#include<stdio.h>
#include<unistd.h>
int main(){
    pid_t pid,pid_1;
    int i = 0;
    printf("Parent running...\n");
    printf("Child process can't print this string.\n");
    pid = fork();
    if(pid == 0){
        printf("Child process b prints: b\n");
        i = 10 ;//Now I change its value from child process!

    }
    if(pid>0){//return from parent process

        i = 12;//Now I change its value from the parent process!

        printf("a\n");
    }
    //Let's print i value

    printf("%d\n",i);//print 10 and 12 will prove my view that child proces

             //has its own data segment.

    pid_1 = fork();//two process will execute this!

    if(pid_1 == 0){
        printf("Child process c prints: c\n");
        i = 11;
        printf("C process print i=%2d\n",i);//print 11

    }
    if(pid_1>0){
        printf("Well two parents print this\n");
    }
}
//the output:
//Parent running...
//Child process can't print this string.
//a
//Child process b prints: b
//12
//10
//Child process c prints: c
//C process print i=11
//Child process c prints: c
//C process print i=11
//Well two parents print this
//Well two parents print this

//Analyze:
//When parent creates a child process , the child proces will share the data
//segment and code segment.But when we write to the parent or child , the child
//process will create its own data segment or code segment.This is called COPYWRITE ?! But I can't sure!

NOTE:  please give your advice for my discovery . Thank you!

NOTE: Thank you for your advice , I agree with you after I have saw some books,you are right.