#include"stdio.h" #include"stdlib.h" #include"string.h" #include "sys/types.h" #include "sys/file.h" #include "unistd.h" char r_buf[4]; char w_buf[4]; int pipe_fd[2]; pid_t pid1, pid2, pid3, pid4; int producer(int id); int consumer(int id); int main(int argc,char **argv) { if(pipe(pipe_fd)<0) { printf("pipe create error \n"); exit(-1); } else { printf("pipe is created successfully!\n"); if((pid1=fork())==0) producer(1); if((pid2=fork())==0) producer(2); if((pid3=fork())==0) consumer(1); if((pid4=fork())==0) consumer(2); } close(pipe_fd[0]); close(pipe_fd[1]); int i,pid,status; for(i=0; i<4; i++) pid=wait(&status); exit(0); } int producer(int id) { printf("producer %d is running!\n",id); close(pipe_fd[0]); int i=0; for(i=1; i<10; i++) { sleep(3); if(id==1) strcpy(w_buf,"aaa\0"); else strcpy(w_buf,"bbb\0"); if(write(pipe_fd[1],w_buf,4)==-1) printf("write to pipe error\n"); } close(pipe_fd[1]); printf("producer %d is over!\n",id); exit(id); } int consumer(int id) { close(pipe_fd[1]); printf(" producer %d is running!\n",id); if (id==1) strcpy(w_buf,"ccc\0"); else strcpy(w_buf,"ddd\0"); while(1) { sleep(1); strcpy(r_buf,"eee\0"); if(read(pipe_fd[0],r_buf,4)==0) break; printf("consumer %d get %s, while the w_buf is %s\n",id,r_buf,w_buf); } close(pipe_fd[0]); printf("consumer %d is over!\n", id); exit(id); }你能和我解释w_buf[4]的作用吗
时间: 2023-06-26 21:09:59 浏览: 64
csapp_深入理解计算机系统_相关文件_csapp.h_csapp.c
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在这个程序中,w_buf[4]的作用是作为写入管道的缓冲区,存储需要写入管道的数据。它的长度为4是因为在这个程序中,每次写入管道的数据都是4字节。在生产者进程中,用strcpy函数将字符串"aaa\0"或"bbb\0"复制到w_buf中,然后通过write函数将w_buf中的数据写入管道。在消费者进程中,通过read函数读取管道中的数据,读取的数据将会存储到r_buf中。因此,w_buf[4]在这个程序中扮演着存储待写入管道数据的角色。
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