多级单父单子进程树？

Question

所以我想编写一个程序来创建多级子进程。单亲和独生子女。

示例：父->child1->child2->child3。像那样。 See image here

但问题是我想从终端获取输入，将创建多少子进程（单父 - 单子进程）。

那么我怎样才能将 嵌套 if 语句修改为某个循环，以便它可以创建我想要的子进程。

这是我的代码

#include<stdio.h>
#include<stdlib.h>
#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
int main() {

int a, b;

    {
        if(fork() == 0)
        {
        printf("child my pid is %d ppid is %d\n",getpid(),getppid());
            if(fork()== 0)
            {
             printf("child my pid is %d ppid is %d\n",getpid(),getppid());
              
               if(fork()== 0)
             {
             printf("child my pid is %d ppid is %d\n",getpid(),getppid());
                }
            }
       
        }
        else
        printf("father my pid is %d ppid is %d\n",getpid(),getppid());
    
    }
    for(int i=0;i<3;i++)
    wait(NULL);

return 0;
}

输出到这里：

father my pid is 4496 ppid is 3621
child my pid is 4497 ppid is 4496
child my pid is 4498 ppid is 4497
child my pid is 4499 ppid is 4498

谢谢，终于成功了。

Answer 1

循环一下：

#include <stdio.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <assert.h>

int main(int argc, char *argv[]) 
{
    assert(argc == 2);
    int num = atoi(argv[1]);
    for (int i = 0; i < num; ++i) {
         int child;
         switch ((child = fork())) { 
         case 0: 
            printf("child my pid is %d ppid is %d\n", getpid(), getppid());
            break;
         case -1:
            fprintf(stderr, "fork failed\n");
            break;
         default:
            printf("father my pid is %d ppid is %d and i just created %d\n",getpid(), getppid(), child);
            i = num; // break of loop
            break;
         }
    }
    wait(NULL);

    return 0;
}

@编辑：

循环中断在错误的位置。现在该流程按预期创建流程树：
使用 gcc 编译代码并运行：

$ ./a.out 5
father my pid is 21893 ppid is 21640 and i just created 21894
child my pid is 21894 ppid is 21893
father my pid is 21894 ppid is 21893 and i just created 21895
child my pid is 21895 ppid is 21894
father my pid is 21895 ppid is 21894 and i just created 21896
child my pid is 21896 ppid is 21895
father my pid is 21896 ppid is 21895 and i just created 21897
child my pid is 21897 ppid is 21896
father my pid is 21897 ppid is 21896 and i just created 21898
child my pid is 21898 ppid is 21897

程序：

• 以 pid 21893 开始
• 使用 pid 21894 创建子节点
• 子 21894 创建子 21895
• 子 21895 创建子 21896
• 子 21896 创建子 21897
• 子 21907 创建子 21898