如何在子进程和父进程之间使用管道

Question

这是我的程序的一部分，其中父进程创建一个管道和分支，并使用管道将父代数字传递给子代。

除了从整数char转换之外，管道和分叉在main中不起作用的问题！

#include <iostream>
#include<sys/types.h>
#include<cstdlib>
#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <string.h>

#include <string>
#include <sstream>
#include <unistd.h>
#include <cstdlib>
#include <sys/wait.h>
#include <assert.h>
#include <sys/types.h>
using namespace std;

int main()
{
        int arr[20];
        char arrCH[20];


        //print process id
        cout << "The current process id is: " << getpid() << endl;

        //random value
        int N = rand()% 10;

        cout << "The genrated random value is: " << N << endl;
        for (int i=1;i<N;i++)
        {
                arr[i] = rand()% 10;
                arrCH[i] = (char)arr[i]; //somthing wrong

        }


        //create a pipe
        int p1[2];
        pipe(p1);

        close(p1[0]);
        write(p1[1],arrCH,strlen(arrCH)+1);

        int r = fork(); //creat a child
        if(r==0)
        {
                cout << "**The fist child**" <<endl;
                close(p1[1]);
                read(p1[0],arrCH,strlen(arrCH));

                //sort the numbers
                //creat another pipe
                //send the sorted numbers to the second child using another pipe

                int r2 = fork();
                if(r2 == 0)
                {
                        cout << "**The second child**" <<endl;

                }
                else
                {
                        wait(NULL);

                 }

                exit(0);
        }
        else
        {
                wait(NULL);

        }

return 0;
}