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枝wenz_fpJNR0 的学生作业：

【图片】

+24
来源：物联网/嵌入式全能工程师（提薪优选） · linux用户管理-学习任务
得分 100
讨论题

lieh1203 的学生作业：

char a = 180; %d输出计算方法 180 = 128 + 32 + 16 + 4 = 1011 0100 -> 原码 因为180是正数，所以补码等于原码，补码：1011 0100 因为%d输出的是原码，所以需把补码转换成原码； 而a为char类型，最高位为1，说明是负数 取反：1100 1011 +1：1100 1100 -> - (0100 1100) -> - (64 + 8 + 4) = - 76 unsigned char b = 300; %d输出计算方法 300 = 256 + 32 + 8 + 4 = 1 0010 1100 -> 原码 因为unsigned char是1bytes，8 bit，超过一个bit了，需把低8bit赋值给b； 补码：0010 1100，因为b一定是正数或者0，所以原码和补码一样 原码：0010 1100 => 32 + 8 + 4 = 44 代码： #include int main() { char a = 180; unsigned char b = 300; printf(“a = %d\n”, a); printf(“b = %d\n”, b); return 0; } 输出： a = -76 b = 44

+10
来源： 物联网/嵌入式全能工程师（提薪优选） · 【讨论题】数据的存储-课后任务
得分 98
讨论题

lieh1203 的学生作业：

#include int main() { int a = 0, b = 0; printf(“Please input two int data:”); scanf("%d,%d", &a, &b); printf(“a = %d\n”, a); printf(“b = %d\n”, b); printf("&a = %p\n", &a); printf("&b = %p\n", &b); return 0; } 输出： Please input two int data:10 20 a = 10 b = 0 &a = 0xff892da4 &b = 0xff892da8

+13
来源： 物联网/嵌入式全能工程师（提薪优选） · 【讨论题】C语言中的输入函数-课后练习
得分 98
讨论题

何青若兰 的学生作业：

30 的原/反/补码：00011110 原码 1100 1101 -30 的原码：10011110 -30 的反码：11100001 -30 的补码：11100010

+43
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

lieh1203 的学生作业：

#include int main() { int a = 10; float b = 3.14; char c = ‘M’; printf(“sizeof(a) = %ld\n”,sizeof(a)); printf(“sizeof(b) = %ld\n”,sizeof(b)); printf(“sizeof© = %ld\n”,sizeof©); printf(“a = %d\n”, a); printf(“b = %f\n”, b); printf(“c = %c\n”, c); return 0; } 输出： sizeof(a) = 4 sizeof(b) = 4 sizeof© = 1 a = 10 b = 3.140000 c = M

+14
来源： 物联网/嵌入式全能工程师（提薪优选） · 【讨论题】C语言中的变量-课后任务
得分 100
讨论题

lieh1203 的学生作业：

练习1： 代码： #include int main() { printf("%c : %d\n", ‘a’, ‘a’); printf("%c : %d\n", ‘m’, ‘m’); printf("%f\n", 3.14159287); printf("%e\n", 31455452232.88232); printf(“data1 = %c : %d\n”, ‘A’+32, ‘A’+32); printf(“data2 = %d\n”, ‘1’ - 48); return 0; } 输出： a : 97 m : 109 3.141593 3.145545e+10 data1 = a : 97 data2 = 1 练习2： 代码： #include #define N 10 #define M N + N int main() { printf(“M = %d\n”, M); printf(“N = %d\n”, N); return 0; } 输出： M = 20 N = 10

+15
来源： 物联网/嵌入式全能工程师（提薪优选） · 【讨论题】C语言中的输出函数-课后任务
得分 100
学习任务

枝wenz_fpJNR0 的学生作业：

【图片】

+22
来源：物联网/嵌入式全能工程师（提薪优选） · ubuntu 软件安装命令详解-课后任务
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

lieh1203 的学生作业：

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
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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; }

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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
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