编写一段源程序，使系统调用fork()创建两个子进程，当此程序运行时，在系统中有

一个父进程和两个子进程活动。让每一个进程在屏幕上显示一个字符：父进程显示字符“a” 子进程分别显示字符“b”和字符“c”。试观察纪录屏幕上的显示结果，并分析原因。-Write a program, make the system call fork () to create two sub process, when running, the system is



A process and the father of two sub process activities. Let each process shows a character on the screen: father process showed the character　a　 the child process respectively show the characters　B　and the character　c . The results of test observation showed the record on the screen, and analyze the reasons.