慕课网-作业社区

得分 98

讨论题

何青若兰的学生作业：

练习1 1001+0011 =1100 1001-0011=0011 练习2 19.25 练习3 100011.10100

+30

来源：物联网/嵌入式全能工程师（提薪优选） · 【讨论题】数据进制的转换-课后任务

得分 100

讨论题

lieh1203 的学生作业：

练习1： -30 原码: 1001 1110 -> 16+8+4+2 反码： 1110 0001 补码： 1110 0010 练习2：补码: 1011 0011 取反: 1100 1100 +1： 1100 1101 原码等于：1100 1101

+14

来源：物联网/嵌入式全能工程师（提薪优选） · 【讨论题】原码、反码、补码的存储-课后任务

得分 100

讨论题

练习1： 1） 1001 0011 1100 2） 1001 -0011 110 练习2： 12^ 0 + 12^ 1 + 12^ 4 + 12^ -2 = 1+2 + 16 + 0.25 = 19.25 练习3： 35 = 32 + 2 + 1 = 12^ 5 + 12^ 1 + 1 *2^ 0 = (100011)2 小数 0.642 = 0.28 -> 1 0.282 = 0.56 -> 0 0.562 = 0.12 -> 1 0.122 = 0.24 -> 0 0.24*2 = 0.48 -> 0 最终等于100011.10100

+11

来源：物联网/嵌入式全能工程师（提薪优选） · 【讨论题】数据进制的转换-课后任务

得分 100

学习任务

慕工程6300203 的学生作业：

client.c #include #include #include #include /* See NOTES */ #include #include #include #include int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } int sockfd, ret; struct sockaddr_in peer_addr; char buffer[1024] = {0}; char *p_buffer = NULL; int len = 0; sockfd = socket(AF_INET, SOCK_STREAM, 0); if(sockfd == -1) { perror("[ERROR] socket"); exit(EXIT_FAILURE); } peer_addr.sin_family = AF_INET; peer_addr.sin_port = htons(atoi(argv[2])); peer_addr.sin_addr.s_addr = inet_addr(argv[1]); ret = connect(sockfd, (struct sockaddr*)&peer_addr, sizeof(peer_addr)); if(ret == -1) { perror("[ERROR] connect"); exit(EXIT_FAILURE); } while (1) { bzero(buffer, sizeof(buffer)); strcpy(buffer, "hello server"); len = strlen(buffer); p_buffer = (char *) malloc(len + 4); memcpy(p_buffer, &len, 4); memcpy(p_buffer + 4, buffer, len); send(sockfd, p_buffer, len + 4, 0); usleep(100); } close(sockfd); return 0; } server.c #include #include #include #include /* See NOTES */ #include #include #include #include #define BACKLOG 10 int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } int sockfd, ret, client_fd; struct sockaddr_in server_addr; struct sockaddr_in client_addr; int len = sizeof(client_addr); char buffer[1024] = {0}; int buffer_len, rbytes, total_recv_len; sockfd = socket(AF_INET, SOCK_STREAM, 0); if(sockfd == -1) { perror("[ERROR] socket"); exit(EXIT_FAILURE); } bzero(&server_addr, sizeof(server_addr)); server_addr.sin_family = AF_INET; server_addr.sin_port = htons(atoi(argv[2])); server_addr.sin_addr.s_addr = inet_addr(argv[1]); ret = bind(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr)); if(ret == -1) { perror("[ERROR] bind"); close(sockfd); exit(EXIT_FAILURE); } ret = listen(sockfd, BACKLOG); if(ret == -1) { perror("[ERROR] listen"); close(sockfd); exit(EXIT_FAILURE); } bzero(&client_addr, sizeof(client_addr)); client_fd = accept(sockfd, (struct sockaddr*)&client_addr, &len); if(ret == -1) { perror("[ERROR] accept"); close(sockfd); exit(EXIT_FAILURE); } while (1) { bzero(buffer, sizeof(buffer)); recv(client_fd, &buffer_len, 4, 0); total_recv_len = 0; while (1) { rbytes = recv(client_fd, buffer + total_recv_len, buffer_len - total_recv_len, 0); if(rbytes > 0) { total_recv_len += rbytes; if(buffer_len == total_recv_len) break; } } printf("recv data: %s\n", buffer); sleep(1); } close(sockfd); close(client_fd); return 0; }

+11

来源：物联网/嵌入式全能工程师（提薪优选） · tcp 粘包解决方案 - 课后任务

得分 100

学习任务

慕工程6300203 的学生作业：

client.c #include #include #include #include /* See NOTES */ #include #include #include #include int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } int sockfd, ret; struct sockaddr_in peer_addr; char buffer[1024] = {0}; sockfd = socket(AF_INET, SOCK_STREAM, 0); if(sockfd == -1) { perror("[ERROR] socket"); exit(EXIT_FAILURE); } peer_addr.sin_family = AF_INET; peer_addr.sin_port = htons(atoi(argv[2])); peer_addr.sin_addr.s_addr = inet_addr(argv[1]); ret = connect(sockfd, (struct sockaddr*)&peer_addr, sizeof(peer_addr)); if(ret == -1) { perror("[ERROR] connect"); exit(EXIT_FAILURE); } while (1) { bzero(buffer, sizeof(buffer)); strcpy(buffer, "hello server"); send(sockfd, buffer, strlen(buffer), 0); usleep(100); } close(sockfd); return 0; } server.c #include #include #include #include /* See NOTES */ #include #include #include #include #define BACKLOG 10 int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } int sockfd, ret, client_fd; struct sockaddr_in server_addr; struct sockaddr_in client_addr; int len = sizeof(client_addr); char buffer[1024] = {0}; sockfd = socket(AF_INET, SOCK_STREAM, 0); if(sockfd == -1) { perror("[ERROR] socket"); exit(EXIT_FAILURE); } bzero(&server_addr, sizeof(server_addr)); server_addr.sin_family = AF_INET; server_addr.sin_port = htons(atoi(argv[2])); server_addr.sin_addr.s_addr = inet_addr(argv[1]); ret = bind(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr)); if(ret == -1) { perror("[ERROR] bind"); close(sockfd); exit(EXIT_FAILURE); } ret = listen(sockfd, BACKLOG); if(ret == -1) { perror("[ERROR] listen"); close(sockfd); exit(EXIT_FAILURE); } bzero(&client_addr, sizeof(client_addr)); client_fd = accept(sockfd, (struct sockaddr*)&client_addr, &len); if(ret == -1) { perror("[ERROR] accept"); close(sockfd); exit(EXIT_FAILURE); } while (1) { bzero(buffer, sizeof(buffer)); recv(client_fd, buffer, sizeof(buffer), 0); printf("recv data: %s\n", buffer); sleep(1); if (strncmp(buffer, "quit", 4) == 0) break; } close(sockfd); close(client_fd); return 0; }

+11

来源：物联网/嵌入式全能工程师（提薪优选） · tcp 粘包原因分析 - 课后任务

得分 100

学习任务

慕工程6300203 的学生作业：

client.c #include #include #include #include /* See NOTES */ #include #include #include #include int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } int sockfd, ret; struct sockaddr_in peer_addr; char buffer[1024] = {0}; sockfd = socket(AF_INET, SOCK_STREAM, 0); if(sockfd == -1) { perror("[ERROR] socket"); exit(EXIT_FAILURE); } peer_addr.sin_family = AF_INET; peer_addr.sin_port = htons(atoi(argv[2])); peer_addr.sin_addr.s_addr = inet_addr(argv[1]); ret = connect(sockfd, (struct sockaddr*)&peer_addr, sizeof(peer_addr)); if(ret == -1) { perror("[ERROR] connect"); exit(EXIT_FAILURE); } while (1) { bzero(buffer, sizeof(buffer)); printf(">"); fgets(buffer, sizeof(buffer), stdin); buffer[strlen(buffer) - 1] = '\0'; send(sockfd, buffer, strlen(buffer), 0); bzero(buffer, sizeof(buffer)); recv(sockfd, buffer, sizeof(buffer), 0); printf("recv: %s\n", buffer); if (strncmp(buffer, "quit", 4) == 0) break; } close(sockfd); return 0; } server.c #include #include #include #include /* See NOTES */ #include #include #include #include #define BACKLOG 10 int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } int sockfd, ret, client_fd; struct sockaddr_in server_addr; struct sockaddr_in client_addr; int len = sizeof(client_addr); char buffer[1024] = {0}; sockfd = socket(AF_INET, SOCK_STREAM, 0); if(sockfd == -1) { perror("[ERROR] socket"); exit(EXIT_FAILURE); } bzero(&server_addr, sizeof(server_addr)); server_addr.sin_family = AF_INET; server_addr.sin_port = htons(atoi(argv[2])); server_addr.sin_addr.s_addr = inet_addr(argv[1]); ret = bind(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr)); if(ret == -1) { perror("[ERROR] bind"); close(sockfd); exit(EXIT_FAILURE); } ret = listen(sockfd, BACKLOG); if(ret == -1) { perror("[ERROR] listen"); close(sockfd); exit(EXIT_FAILURE); } bzero(&client_addr, sizeof(client_addr)); client_fd = accept(sockfd, (struct sockaddr*)&client_addr, &len); if(ret == -1) { perror("[ERROR] accept"); close(sockfd); exit(EXIT_FAILURE); } while (1) { bzero(buffer, sizeof(buffer)); recv(client_fd, buffer, sizeof(buffer), 0); printf("recv data: %s\n", buffer); send(client_fd, buffer, strlen(buffer), 0); if (strncmp(buffer, "quit", 4) == 0) break; } close(sockfd); close(client_fd); return 0; }

+11

来源：物联网/嵌入式全能工程师（提薪优选） · 数据接收与发送 - 课后练习

得分 100

学习任务

学无止境呀呀呀的学生作业：

#include #include #include #include #include #include #include #include #define size 1024 struct shmseg { size_t nbytes; char data[size]; }; int main(void) { int shmid; char src[256]; char dst[256]; //创建k key_t k = ftok(".",2); if(k == -1) { perror("[ERROR] ftok:"); exit(EXIT_FAILURE); } //创建共享内存 shmid = shmget(k,sizeof (struct shmseg),IPC_CREAT|0666); if(shmid == -1) { perror("[ERROR] shmid:"); exit(EXIT_FAILURE); } //关联映射 struct shmseg *seg = shmat(shmid,NULL,0); if(seg == (void *)-1) { perror("shmat():"); exit(EXIT_FAILURE); } printf("请输入要传输的文件和目的地:\n"); fflush(stdout); if(scanf("%s%s",src,dst) != 2){ printf("请输入要传输的文件和目的地(空格分离):\n"); exit(EXIT_FAILURE); } pid_t child = fork(); if(child == -1) { perror("fork():"); exit(EXIT_FAILURE); } else if(child == 0) { char buff[size]; size_t rbytes; //子进程 //发送文件 FILE *in = fopen(src,"r"); if(!in) { perror("fopen():"); exit(EXIT_FAILURE); } //把文件in里的数据读到seg->data,记录读了多少字节 seg->nbytes = fread(seg->data,sizeof(char),size,in); if(seg->nbytes == 0 && ferror(in)) { perror("read"); fclose(in); exit(EXIT_FAILURE); } printf("子进程存入完毕, 共%ld字节\n",seg->nbytes); fclose(in); exit(EXIT_SUCCESS); } else { waitpid(child,NULL,0);//等待子进程执行结束 //读取文件 FILE *out = fopen(dst,"wb"); if(!out) { perror("fopen(dst)"); exit(EXIT_FAILURE); } //把seg->data里有效字节写入out文件 if(fwrite(seg->data,sizeof(char),seg->nbytes,out) != seg->nbytes) { perror("write():"); fclose(out); exit(EXIT_FAILURE); } printf("父进程写入完毕,共%ld字节\n",seg->nbytes); fclose(out); } //解除映射 if(shmdt(seg) == -1) { perror("shmdt():"); exit(EXIT_FAILURE); } //删除共享内存shmctl int ret = shmctl(shmid,IPC_RMID,NULL); if(ret == -1) { perror("shmctl():"); exit(EXIT_FAILURE); } return 0; }

+78

来源：物联网/嵌入式工程师 · 共享内存的映射与解除映射-课后练习

得分 100

学习任务

慕工程6300203 的学生作业：

#include #include #include #include /* See NOTES */ #include #include #include #include #define BACKLOG 10 int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } int sockfd, ret, client_fd; struct sockaddr_in server_addr; struct sockaddr_in client_addr; int len = sizeof(client_addr); sockfd = socket(AF_INET, SOCK_STREAM, 0); if(sockfd == -1) { perror("[ERROR] socket"); exit(EXIT_FAILURE); } bzero(&server_addr, sizeof(server_addr)); server_addr.sin_family = AF_INET; server_addr.sin_port = htons(atoi(argv[2])); server_addr.sin_addr.s_addr = inet_addr(argv[1]); ret = bind(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr)); if(ret == -1) { perror("[ERROR] bind"); close(sockfd); exit(EXIT_FAILURE); } ret = listen(sockfd, BACKLOG); if(ret == -1) { perror("[ERROR] listen"); close(sockfd); exit(EXIT_FAILURE); } bzero(&client_addr, sizeof(client_addr)); client_fd = accept(sockfd, (struct sockaddr*)&client_addr, &len); if(ret == -1) { perror("[ERROR] accept"); close(sockfd); exit(EXIT_FAILURE); } close(sockfd); close(client_fd); return 0; }

+10

来源：物联网/嵌入式全能工程师（提薪优选） · 建立监听队列与接收连接 - 课后练习

得分 100

学习任务

慕工程6300203 的学生作业：

#include #include #include #include /* See NOTES */ #include #include #include #include int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } int sockfd, ret; struct sockaddr_in server_addr; sockfd = socket(AF_INET, SOCK_STREAM, 0); if(sockfd == -1) { perror("[ERROR] socket"); exit(EXIT_FAILURE); } bzero(&server_addr, sizeof(server_addr)); server_addr.sin_family = AF_INET; server_addr.sin_port = htons(atoi(argv[2])); server_addr.sin_addr.s_addr = inet_addr(argv[1]); ret = bind(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr)); if(ret == -1) { perror("[ERROR] bind"); exit(EXIT_FAILURE); } close(sockfd); return 0; }

+11

来源：物联网/嵌入式全能工程师（提薪优选） · 创建套接字、绑定ip地址与端口号 - 课后练习

得分 100

学习任务

慕工程6300203 的学生作业：

#include #include #include #include /* See NOTES */ #include #include #include #include int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } int sockfd, ret; struct sockaddr_in peer_addr; char buffer[1024] = {0}; sockfd = socket(AF_INET, SOCK_STREAM, 0); if(sockfd == -1) { perror("[ERROR] socket"); exit(EXIT_FAILURE); } peer_addr.sin_family = AF_INET; peer_addr.sin_port = htons(atoi(argv[2])); peer_addr.sin_addr.s_addr = inet_addr(argv[1]); ret = connect(sockfd, (struct sockaddr*)&peer_addr, sizeof(peer_addr)); if(ret == -1) { perror("[ERROR] connect"); exit(EXIT_FAILURE); } while (1) { bzero(buffer, sizeof(buffer)); printf(">"); fgets(buffer, sizeof(buffer), stdin); buffer[strlen(buffer) - 1] = '\0'; send(sockfd, buffer, strlen(buffer), 0); if (strncmp(buffer, "quit", 4) == 0) break; } close(sockfd); return 0; }

+12

来源：物联网/嵌入式全能工程师（提薪优选） · tcp 客户端发送与接收数据 - 课后任务

得分 100

学习任务

慕工程6300203 的学生作业：

#include #include #include #include /* See NOTES */ #include #include #include #include int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } int sockfd, ret; struct sockaddr_in peer_addr; char buffer[1024] = {0}; sockfd = socket(AF_INET, SOCK_STREAM, 0); if(sockfd == -1) { perror("[ERROR] socket"); exit(EXIT_FAILURE); } peer_addr.sin_family = AF_INET; peer_addr.sin_port = htons(atoi(argv[2])); peer_addr.sin_addr.s_addr = inet_addr(argv[1]); ret = connect(sockfd, (struct sockaddr*)&peer_addr, sizeof(peer_addr)); if(ret == -1) { perror("[ERROR] connect"); exit(EXIT_FAILURE); } while (1) { bzero(buffer, sizeof(buffer)); printf(">"); fgets(buffer, sizeof(buffer), stdin); buffer[strlen(buffer) - 1] = '\0'; send(sockfd, buffer, strlen(buffer), 0); if (strncmp(buffer, "quit", 4) == 0) break; } close(sockfd); return 0; }

+12

来源：物联网/嵌入式全能工程师（提薪优选） · tcp 客户端实现流程与服务器连接 - 课后任务

得分 100

学习任务

cjozGV 的学生作业：

#include #include using namespace std; class String{ public: String(const char* s){ len = strlen(s); data = new char[len + 1]; strcpy(data,s); } ~String(){ delete[] data; } char& operator[](int index){ return data[index]; } const char& operator[](int index) const { return data[index]; } int size() const { return len; } // 让友元函数可以访问 data friend ostream& operator

+10

来源：物联网/嵌入式全能工程师（提薪优选） · 特殊运算符重载及注意点 - 课后任务

得分 100

学习任务

慕工程6300203 的学生作业：

#include #include #include #include #include #include #include #include #include #include #include #define LOGIN_SUCCESS 1 #define LOGIN_FAILURE 0 typedef struct { char *ip; int login_flag; struct sockaddr_in peer_addr; } pthread_argv_t; void recv_data(int fd) { char buffer[1024] = {0}; struct sockaddr_in client_addr; socklen_t len = sizeof(client_addr); int ret = 0; while(1) { memset(buffer, 0, sizeof(buffer)); ret = recvfrom(fd, buffer, sizeof(buffer), 0, (struct sockaddr *)&client_addr, &len); if (ret < 0) { perror("[ERROR] recvfrom"); exit(EXIT_FAILURE); } printf("============================\n"); printf("Recvfrom IP: %s\n", inet_ntoa(client_addr.sin_addr)); printf("Recvfrom PORT: %d\n", ntohs(client_addr.sin_port)); printf("Received data: %s\n", buffer); if (strncmp(buffer, "quit", 4) == 0) break; } close(fd); } int init_socket(char *ip, char *port) { int socket_fd; struct sockaddr_in connect_addr; int ret; socket_fd = socket(AF_INET, SOCK_DGRAM, 0); if(socket_fd == -1) { perror("[ERROR] Socket Create Failed"); exit(EXIT_FAILURE); } memset(&connect_addr, 0, sizeof(connect_addr)); connect_addr.sin_family = AF_INET; connect_addr.sin_port = htons(atoi(port)); connect_addr.sin_addr.s_addr = inet_addr(ip); ret = bind(socket_fd, (struct sockaddr *)&connect_addr, sizeof(connect_addr)); if (ret < 0) { perror("[ERROR] Bind Failed"); exit(EXIT_FAILURE); } return socket_fd; } void *thread_func(void *arg) { pthread_argv_t *pthread_argv = (pthread_argv_t *)arg; char *ip = pthread_argv->ip; struct sockaddr_in client_addr = pthread_argv->peer_addr; int login_flag = pthread_argv->login_flag; int len = sizeof(client_addr); int new_socket_fd = init_socket(ip,"0"); sendto(new_socket_fd, &login_flag, sizeof(login_flag), 0, (struct sockaddr *)&client_addr, len); recv_data(new_socket_fd); pthread_exit(NULL); } void user_login(char *ip, char *port) { int socket_fd; // 这里原本定义指针，到thread_func中后，由于user_login已经结束， // 这个局部变量失效了，导致服务端发送登录成功消息时，客户端无法接收到信息 struct sockaddr_in client_addr; int len = sizeof(client_addr); int ret = 0; pthread_t tid; pthread_argv_t pthread_argv; char buffer[1024] = {0}; int login_flag = LOGIN_FAILURE; socket_fd = init_socket(ip, port); printf("wait for login\n"); while(1) { memset(buffer, 0, sizeof(buffer)); ret = recvfrom(socket_fd, buffer, sizeof(buffer), 0, (struct sockaddr *)&client_addr, &len); if (ret < 0) { perror("[ERROR] Recv Failed"); exit(EXIT_FAILURE); } printf("key = %s\n", buffer); login_flag = strncmp(buffer, "password", 8) == 0 ? LOGIN_SUCCESS : LOGIN_FAILURE; if (login_flag == LOGIN_SUCCESS) { pthread_argv.login_flag = login_flag; pthread_argv.ip = ip; pthread_argv.peer_addr = client_addr; pthread_create(&tid, NULL, thread_func, &pthread_argv); } else { sendto(socket_fd, &login_flag, sizeof(login_flag), 0, (struct sockaddr *)&client_addr, len); } pthread_detach(tid); } } int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } user_login(argv[1], argv[2]); return 0; }

+12

来源：物联网/嵌入式全能工程师（提薪优选） · 并发服务器之多线程并发 - 课后任务

得分 100

学习任务

慕工程6300203 的学生作业：

#include #include #include #include #include #include #include #include #include #include #define LOGIN_SUCCESS 1 #define LOGIN_FAILURE 0 void recv_data(int fd) { char buffer[1024] = {0}; struct sockaddr_in client_addr; int len = sizeof(client_addr); int ret; while(1) { memset(buffer, 0, sizeof(buffer)); ret = recvfrom(fd, buffer, sizeof(buffer), 0, (struct sockaddr *)&client_addr, &len); if (ret < 0) { perror("[ERROR] recvfrom"); exit(EXIT_FAILURE); } printf("============================\n"); printf("Recvfrom IP: %s\n", inet_ntoa(client_addr.sin_addr)); printf("Recvfrom PORT: %d\n", ntohs(client_addr.sin_port)); printf("Received data: %s\n", buffer); if (strncmp(buffer, "quit", 4) == 0) break; } close(fd); exit(EXIT_SUCCESS); } int init_socket(char *ip, char *port) { int socket_fd; struct sockaddr_in connect_addr; int ret; socket_fd = socket(AF_INET, SOCK_DGRAM, 0); if(socket_fd == -1) { perror("[ERROR] Socket Create Failed"); exit(EXIT_FAILURE); } memset(&connect_addr, 0, sizeof(connect_addr)); connect_addr.sin_family = AF_INET; connect_addr.sin_port = htons(atoi(port)); connect_addr.sin_addr.s_addr = inet_addr(ip); ret = bind(socket_fd, (struct sockaddr *)&connect_addr, sizeof(connect_addr)); if (ret < 0) { perror("[ERROR] Bind Failed"); exit(EXIT_FAILURE); } return socket_fd; } int user_login(char *ip, char *port) { int socket_fd, new_socket_fd; struct sockaddr_in client_addr; int len = sizeof(client_addr); int ret; pid_t cpid; char buffer[20] = {0}; int login_flag = LOGIN_FAILURE; socket_fd = init_socket(ip, port); while(1) { memset(buffer, 0, sizeof(buffer)); ret = recvfrom(socket_fd, buffer, sizeof(buffer), 0, (struct sockaddr *)&client_addr, &len); if (ret < 0) { perror("[ERROR] Recv Failed"); exit(EXIT_FAILURE); } login_flag = strncmp(buffer, "password", 8) == 0 ? LOGIN_SUCCESS : LOGIN_FAILURE; if (login_flag == LOGIN_SUCCESS) { cpid = fork(); if(cpid == 0) { close(socket_fd); new_socket_fd = init_socket(ip,"0"); sendto(new_socket_fd, &login_flag, sizeof(login_flag), 0, (struct sockaddr *)&client_addr, len); break; } } else { sendto(socket_fd, &login_flag, sizeof(login_flag), 0, (struct sockaddr *)&client_addr, len); } } return new_socket_fd; } void sig_handle(int signum) { waitpid(-1, NULL, WNOHANG); printf("recv singnum = %d zombie\n", signum); } int main(int argc, char* argv[]) { if(argc != 3) { printf("Usage : %s \n", argv[0]); exit(EXIT_FAILURE); } if (signal(SIGCHLD, sig_handle) == SIG_ERR) { perror("[ERROR] Signal Handle Error"); return -1; } int socket_fd = user_login(argv[1], argv[2]); recv_data(socket_fd); return 0; }

+12

来源：物联网/嵌入式全能工程师（提薪优选） · 并发服务器之多进程并发 - 课后任务

得分 99

项目作业

anqilin 的作业评语：

同学作业基本满足作业要求。只是作业要求至少爬取5页，因为是随机显示一条数据，所以我们至少请求5次来代替5页数据，同学代码只爬取了一条数据，同学可以用for循环多请求几次，参考代码请看批复文档

来源：Python全能工程师 · 【项目作业】Scrapy框架Scrapy架构爬虫实战

得分 100

学习任务

cjozGV 的学生作业：

#include #include using namespace std; class String{ public: // 构造函数 String(const char* s){ len = strlen(s); data = new char[len + 1]; strcpy(data,s); } // 析构函数 ~String(){ delete[] data; } // 重载下标运算符(可修改) char& operator[](int index){ return data[index]; } // 重载下标运算符(可读) char& operator[](int index) const{ return data[index]; } // 返回长度 int size() const{ return len; } private: char* data; int len; }; int main(){ String str("hello"); str[0] = 'w'; str[1] = 'x'; for (int i = 0; i < str.size(); i++) { cout

+10

来源：物联网/嵌入式全能工程师（提薪优选） · 运算符重载- 课后任务

得分 100

学习任务

cjozGV 的学生作业：

#include using namespace std; // 提前声明 Test，因为 FriendClass 要用到它 class Test; // 1 FriendClass 必须完整定义在前 class FriendClass { public: void memberFunc(const Test &obj); // 成员函数声明 void show(const Test &obj); // 成员函数声明 private: int a; int b; }; // 2 Test 类放在 FriendClass 后面 class Test { public: Test(int a, int b) : a(a), b(b) {} // 1. 友元函数 friend void friendFunction(const Test &obj); // 2. 友元成员函数（此时 FriendClass 已经完整定义） friend void FriendClass::memberFunc(const Test &obj); // 3. 友元类 friend class FriendClass; private: int a; int b; }; // 3 友元函数定义 void friendFunction(const Test &obj) { cout

+13

来源：物联网/嵌入式全能工程师（提薪优选） · firend友元 - 课后练习

得分 100

学习任务

cjozGV 的学生作业：

1.构造函数和析构函数不能用 static 或 const 修饰，因为它们必须依赖对象本身 2.成员变量可以用 static const 修饰，表示“类常量” 3.成员函数不能用 static const 修饰，因为语义冲突

+12

来源：物联网/嵌入式全能工程师（提薪优选） · C++ const关键字 - 课后练习

得分 100

讨论题

zhuluoc 的学生作业：

// linkstack.h #ifndef __SEQSTACK_H__ #define __SEQSTACK_H__ #include #include #include typedef char data_t; typedef struct node { data_t data; struct node *next; } stacknode_t; // 顺序栈数据类型 typedef struct { stacknode_t *top; // 栈顶指针 int icnt; // 栈中元素个数 } linkstack_t; //------------------------------------------------ // 创建空栈 extern linkstack_t * create_seqstack(); // 判断栈是否为空 extern int is_empty_seqstack(linkstack_t *s); // 元素入栈 extern int push_seqstack(linkstack_t *s, data_t data); // 元素出栈 extern data_t pop_seqstack(linkstack_t *s); // 获得栈顶元素 extern data_t top_seqstack(linkstack_t *s); #endif // linkstack.c #include "linkstack.h" // 创建空栈 linkstack_t * create_seqstack() { linkstack_t *s = (linkstack_t *)malloc(sizeof(linkstack_t)); if (NULL == s) { printf("malloc error!\n"); return NULL; } memset(s, 0, sizeof(linkstack_t)); s->top = NULL; // 设置为栈 s->icnt = 0; return s; } //------------------------------------------------ // 判断栈是否为空 int is_empty_seqstack(linkstack_t *s) { return (s->top == NULL ? 1 : 0); } //------------------------------------------------ // 元素入栈 int push_seqstack(linkstack_t *s, data_t data) { stacknode_t *t = NULL; t = (stacknode_t *)malloc(sizeof(stacknode_t)); if (NULL == t) { printf("malloc error!\n"); return -1; } t->data = data; // 插入数据 t->next = s->top; s->top = t; s->icnt++; return 0; } //------------------------------------------------ // 元素出栈 data_t pop_seqstack(linkstack_t *s) { data_t data; stacknode_t *t = NULL; // 取出栈顶指针 t = s->top; // 更新栈顶指针 s->top = t->next; data = t->data; free(t); t = NULL; s->icnt--; return data; } //------------------------------------------------ // 获得栈顶元素 data_t top_seqstack(linkstack_t *s) { return s->top->data; } //------------------------------------------------ // main.c #include "linkstack.h" int main() { int i = 0; data_t ret = 0; data_t data[] = {'a','n','i','h','c',' ','e','v','o','l',' ','I'}; // 创建顺序栈 linkstack_t *s = create_seqstack(); if (NULL == s) return -1; for (i = 0; i < sizeof(data) / sizeof(data[0]); i++) { push_seqstack(s, data[i]); } printf("pop stack:\n"); while (!is_empty_seqstack(s)) { ret = pop_seqstack(s); printf("%c ", ret); } printf("\n"); return 0; } 输出结果： pop stack: I l o v e c h i n a

+26