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目录
exec函数族：
man 3 exec 说明 实例如下：
– “l”和“v”表示参数是以列表还是以数组的方式提供的
– “p”表示这个函数的第一个参数是*path，就是以绝对路径来提供程序的
路径，也可以以当前目录作为目标
– “e”表示为程序提供新的环境变量
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include <unistd.h>
//exec函数族
int main(void)
{
if(execl("/mnt/udisk/helloexec","helloexec","execl",NULL) == -1){
perror("execl error");
exit(1);
}
//程序已经跳转走，如果正常execl不反回错误，下面的代码不会执行！
printf("execl error！\n");
return 0;
}fork创建新进程
pid_t fork(void); 返回子进程的id号
#include <stdio.h>
#include <unistd.h>
main()
{
pid_t pid;
int i=100;
pid = fork();
//调用出错
if(pid == -1){
printf("fork failed\n");
return 1;
}
//返回给父进程子进程号，返回值大于0
else if(pid){
i++;
printf("\nThe father i = %d\n",i);
printf("The father return value is %d\n",pid);
printf("The father pid is %d\n",getpid());
printf("The father ppid is %d\n",getppid());
while(1);
}
//返回子进程0，返回值等于0返回给子进程
else{
i++;
printf("\nThe child i = %d\n",i);
printf("The child return value is %d\n",pid);
printf("The child pid is %d\n",getpid());
printf("The child ppid is %d\n",getppid());
while(1);
}
return 0;
}无名管道man 7 pipe：
int pipe(int pipefd[2])
– 参数pipefd[0]：用于读管道
– 参数pipefd[1]：用于写管道
– 返回值：执行成功返回0，失败返回-1
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
//进程读函数
void read_data(int *);
//进程写函数
void write_data(int *);
int main(int argc,char *argv[])
{
int pipes[2],rc;
pid_t pid;
rc = pipe(pipes); //创建管道
if(rc == -1){
perror("\npipes\n");
exit(1);
}
pid = fork(); //创建进程
switch(pid){
case -1:
perror("\nfork\n");
exit(1);
case 0:
read_data(pipes); //相同的pipes
default:
write_data(pipes); //相同的pipes
}
return 0;
}
//进程读函数
void read_data(int pipes[])
{
int c,rc;
//由于此函数只负责读，因此将写描述关闭(资源宝贵)
close(pipes[1]);
//阻塞，等待从管道读取数据
//int 转为 unsiged char 输出到终端
while( (rc = read(pipes[0],&c,1)) > 0 ){
putchar(c);
}
exit(0);
}
//进程写函数
void write_data(int pipes[])
{
int c,rc;
//关闭读描述字
close(pipes[0]);
while( (c=getchar()) > 0 ){
rc = write( pipes[1], &c, 1); //写入管道
if( rc == -1 ){
perror("Parent: write");
close(pipes[1]);
exit(1);
}
}
close( pipes[1] );
exit(0);
}
有名管道man 3 mkfifo:
• int mkfifo(const char *pathname, mode_t mode)
– 参数*pathname：路径名，管道名称
– 参数mode：管道的权限
– 返回值：成功返回0，错误返回-1
创建
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
void filecopy(FILE *,char *);
int main(void)
{
FILE *fp1;
long int i = 100000;
char buf[] = "I want to study Linux!\n";
char *file1 = "data.txt";
printf("begin!\n");
if((fp1 = fopen(file1,"a+")) == NULL ){
printf("can't open %s\n",file1);
}
while(i--)
filecopy(fp1,buf);
fclose(fp1);
printf("over!\n");
return 0;
}
void filecopy(FILE *ifp,char *buf)
{
char c;
int i,j;
j = 0;
i = strlen(buf)-1;
while(i--){
putc(buf[j],ifp);
j++;
}
putc('\n',ifp);
}
读取
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <limits.h>
#include <string.h>
int main()
{
const char *fifo_name = "my_fifo";
int pipe_fd = -1;
int data_fd = -1;
int res = 0;
int open_mode = O_RDONLY;
char buffer[PIPE_BUF + 1];
int bytes_read = 0;
int bytes_write = 0;
//清空缓冲数组
memset(buffer, '\0', sizeof(buffer));
printf("Process %d opening FIFO O_RDONLY\n", getpid());
//以只读阻塞方式打开管道文件，注意与fifowrite.c文件中的FIFO同名
pipe_fd = open(fifo_name, open_mode);
//以只写方式创建保存数据的文件
data_fd = open("DataFormFIFO.txt", O_WRONLY|O_CREAT, 0644);
printf("Process %d result %d\n",getpid(), pipe_fd);
if(pipe_fd != -1)
{
do
{
//读取FIFO中的数据，并把它保存在文件DataFormFIFO.txt文件中
res = read(pipe_fd, buffer, PIPE_BUF);
bytes_write = write(data_fd, buffer, res);
bytes_read += res;
}while(res > 0);
close(pipe_fd);
close(data_fd);
}
else
exit(EXIT_FAILURE);
printf("Process %d finished, %d bytes read\n", getpid(), bytes_read);
exit(EXIT_SUCCESS);
}
写入：
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <string.h>
int main()
{
const char *fifo_name = "my_fifo";
char *file1 = "data.txt";
int pipe_fd = -1;
int data_fd = -1;
int res = 0;
const int open_mode = O_WRONLY;
int bytes_sent = 0;
char buffer[PIPE_BUF + 1];
if(access(fifo_name, F_OK) == -1)
{
//管道文件不存在
//创建命名管道
res = mkfifo(fifo_name, 0777);
if(res != 0)
{
fprintf(stderr, "Could not create fifo %s\n", fifo_name);
exit(EXIT_FAILURE);
}
}
printf("Process %d opening FIFO O_WRONLY\n", getpid());
//以只写阻塞方式打开FIFO文件，以只读方式打开数据文件
pipe_fd = open(fifo_name, open_mode);
data_fd = open(file1, O_RDONLY);
printf("Process %d result %d\n", getpid(), pipe_fd);
if(pipe_fd != -1)
{
int bytes_read = 0;
//向数据文件读取数据
bytes_read = read(data_fd, buffer, PIPE_BUF);
buffer[bytes_read] = '\0';
while(bytes_read > 0)
{
//向FIFO文件写数据
res = write(pipe_fd, buffer, bytes_read);
if(res == -1)
{
fprintf(stderr, "Write error on pipe\n");
exit(EXIT_FAILURE);
}
//累加写的字节数，并继续读取数据
bytes_sent += res;
bytes_read = read(data_fd, buffer, PIPE_BUF);
buffer[bytes_read] = '\0';
}
close(pipe_fd);
close(data_fd);
}
else
exit(EXIT_FAILURE);
printf("Process %d finished\n", getpid());
exit(EXIT_SUCCESS);
}
消息队列：
函数ssize_t msgrcv(int msqid, void *msgp, size_t msgsz, long
msgtyp,int msgflg)
– 参数msqid：消息队列的标识码
– 参数*msgp：指向消息缓冲区的指针
– 参数msgsz：消息的长短
– 参数msgflg：标志位
– 返回值：成功返回数据长度，错误返回-1
• 函数int msgsnd(int msqid, const void *msgp, size_t msgsz, int
msgflg)
– 参数msqid：消息队列的标识码
– 参数*msgp：指向消息缓冲区的指针，此位置用来暂时存储发送和接收
的消息，是一个用户可定义的通用结构
– 参数msgsz：消息的长短
– 参数msgflg：标志位
– 返回值：成功返回0，错误返回-1
• 结构体msgp，是一个标准的通用结构
– struct msgstru{
long mtype; //大于0
char mtext[nbyte];}
• 函数int msgget(key_t key, int msgflg)
– 参数“key”：消息队列关联的标识符
– 参数“msgflg”：消息队列的建立标志和存取权限。IPC_CREAT 如果内核
中没有此队列则创建它；IPC_EXCL 当和IPC_CREAT 一起使用时，如果
队列已经存在，则失败
– 返回值：执行成功则返回消息队列的标识符，否则返回-1
• 函数ssize_t msgrcv(int msqid, void *msgp, size_t msgsz, long
msgtyp,int msgflg)
– 参数msgtyp
• msgtyp等于0 ,则返回队列的最早的一个消息
• msgtyp大于0，则返回其类型为mtype的第一个消息
• msgtyp小于0,则返回其类型小于或等于mtype参数的绝对值的最小的一个消
息
– 参数msgflg：标志位为0，则表示忽略
发送例子
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/msg.h>
#include <errno.h>
#define MAX_TEXT 512
struct msg_st
{
long int msg_type;
char text[MAX_TEXT];
};
int main()
{
int running = 1;
struct msg_st data;
char buffer[BUFSIZ];
int msgid = -1;
//建立消息队列
msgid = msgget((key_t)1234, 0666 | IPC_CREAT);
if(msgid == -1)
{
fprintf(stderr, "msgget failed with error: %d\n", errno);
exit(EXIT_FAILURE);
}
//向消息队列中写消息，直到写入end
while(running)
{
//输入数据
printf("Enter some text: ");
fgets(buffer, BUFSIZ, stdin);
data.msg_type = 1; //注意2
strcpy(data.text, buffer);
//向队列发送数据
if(msgsnd(msgid, (void*)&data, MAX_TEXT, 0) == -1)
{
fprintf(stderr, "msgsnd failed\n");
exit(EXIT_FAILURE);
}
//输入end结束输入
if(strncmp(buffer, "end", 3) == 0)
running = 0;
sleep(1);
}
exit(EXIT_SUCCESS);
}
接受例子
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/msg.h>
struct msg_st
{
long int msg_type;
char text[BUFSIZ];
};
int main()
{
int running = 1;
int msgid = -1;
struct msg_st data;
long int msgtype = 0; //注意1
//建立消息队列
msgid = msgget((key_t)1234, 0666 | IPC_CREAT);
if(msgid == -1)
{
fprintf(stderr, "msgget failed with error: %d\n", errno);
exit(EXIT_FAILURE);
}
//从队列中获取消息，直到遇到end消息为止
while(running)
{
if(msgrcv(msgid, (void*)&data, BUFSIZ, msgtype, 0) == -1)
{
fprintf(stderr, "msgrcv failed with errno: %d\n", errno);
exit(EXIT_FAILURE);
}
printf("You wrote: %s\n",data.text);
//遇到end结束
if(strncmp(data.text, "end", 3) == 0)
running = 0;
}
//删除消息队列
if(msgctl(msgid, IPC_RMID, 0) == -1)
{
fprintf(stderr, "msgctl(IPC_RMID) failed\n");
exit(EXIT_FAILURE);
}
exit(EXIT_SUCCESS);
}
信号：
• unsigned int alarm(unsigned int seconds)
– 参数seconds：闹钟的时间，单位为秒
– 返回值：成功返回0 或者返回剩余时间；错误返回-1
• sighandler_t signal(int signum, sighandler_t handler);
– 参数signum：等待的信号
– 参数handler：信号到来之后，触发的处理方式
– 返回值：成功返回0，错误返回-1
简单例子：
#include<unistd.h>
#include<stdio.h>
#include<signal.h>
void handler()
{
printf("hello\n");
}
int main(void)
{
int i;
signal(SIGALRM, handler);
alarm(5);
for(i=1;i<7;i++){
printf("sleep %d....\n",i);
sleep(1);
}
return 0;
}复杂例子
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <stdlib.h>
#include <stdio.h>
void handler(int sig)
{
printf("Handler the signal %d\n", sig);
}
int main(void)
{
sigset_t sigset;//用于记录屏蔽字
sigset_t ign;//用于记录被阻塞的信号集
struct sigaction act;
//清空信号集
sigemptyset(&sigset); //初始化信号集
sigemptyset(&ign);
//向信号集中添加信号SIGINT
sigaddset(&sigset, SIGINT);
//设置处理函数和信号集
act.sa_handler = handler;
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
sigaction(SIGINT, &act, 0);
printf("Wait the signal SIGINT...\n");
pause();//挂起进程，等待信号
//设置进程屏蔽字，在本例中为屏蔽SIGINT
sigprocmask(SIG_SETMASK, &sigset, 0);
printf("Please press Ctrl+c in 10 seconds...\n");
sleep(10);
//测试SIGINT是否被屏蔽
sigpending(&ign);
if(sigismember(&ign, SIGINT))
printf("The SIGINT signal has ignored\n");
//在信号集中删除信号SIGINT
sigdelset(&sigset, SIGINT);
printf("Wait the signal SIGINT...\n");
//将进程的屏蔽字重新设置，即取消对SIGINT的屏蔽
//并挂起进程
sigsuspend(&sigset);
printf("The app will exit in 5 seconds!\n");
sleep(5);
exit(0);
}
信号量：
例子：
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/sem.h>
union semun
{
int val;
struct semid_ds *buf;
unsigned short *arry;
};
static int sem_id = 0;
static int set_semvalue();
static void del_semvalue();
static int semaphore_p();
static int semaphore_v();
int main(int argc, char *argv[])
{
char message = 'X';
int i = 0;
//创建信号量
sem_id = semget((key_t)1234, 1, 0666 | IPC_CREAT);
if(argc > 1)
{
//程序第一次被调用，初始化信号量
if(!set_semvalue())
{
fprintf(stderr, "Failed to initialize semaphore\n");
exit(EXIT_FAILURE);
}
//设置要输出到屏幕中的信息，即其参数的第一个字符
message = argv[1][0];
sleep(2);
}
for(i = 0; i < 10; ++i)
{
//进入临界区
if(!semaphore_p())
exit(EXIT_FAILURE);
//向屏幕中输出数据
printf("%c", message);
//清理缓冲区，然后休眠随机时间
fflush(stdout);
sleep(rand() % 3);
//离开临界区前再一次向屏幕输出数据
printf("%c", message);
fflush(stdout);
//离开临界区，休眠随机时间后继续循环
if(!semaphore_v())
exit(EXIT_FAILURE);
sleep(rand() % 2);
}
sleep(10);
printf("\n%d - finished\n", getpid());
if(argc > 1)
{
//如果程序是第一次被调用，则在退出前删除信号量
sleep(3);
del_semvalue();
}
exit(EXIT_SUCCESS);
}
static int set_semvalue()
{
//用于初始化信号量，在使用信号量前必须这样做
union semun sem_union;
sem_union.val = 1;
if(semctl(sem_id, 0, SETVAL, sem_union) == -1)
return 0;
return 1;
}
static void del_semvalue()
{
//删除信号量
union semun sem_union;
if(semctl(sem_id, 0, IPC_RMID, sem_union) == -1)
fprintf(stderr, "Failed to delete semaphore\n");
}
static int semaphore_p()
{
//对信号量做减1操作，即等待P（sv）
struct sembuf sem_b;
sem_b.sem_num = 0;
sem_b.sem_op = -1;//P()
sem_b.sem_flg = SEM_UNDO;
if(semop(sem_id, &sem_b, 1) == -1)
{
fprintf(stderr, "semaphore_p failed\n");
return 0;
}
return 1;
}
static int semaphore_v()
{
//这是一个释放操作，它使信号量变为可用，即发送信号V（sv）
struct sembuf sem_b;
sem_b.sem_num = 0;
sem_b.sem_op = 1;//V()
sem_b.sem_flg = SEM_UNDO;
if(semop(sem_id, &sem_b, 1) == -1)
{
fprintf(stderr, "semaphore_v failed\n");
return 0;
}
return 1;
}
共享内存：
写入例子
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/shm.h>
#include "shmdata.h"
int main(void)
{
int running = 1;//程序是否继续运行的标志
void *shm = NULL;//分配的共享内存的原始首地址
struct shared_use_st *shared;//指向shm
int shmid;//共享内存标识符
//创建共享内存
shmid = shmget((key_t)1234, sizeof(struct shared_use_st), 0666|IPC_CREAT);
if(shmid == -1)
{
fprintf(stderr, "shmget failed\n");
exit(EXIT_FAILURE);
}
//将共享内存连接到当前进程的地址空间
shm = shmat(shmid, 0, 0);
if(shm == (void*)-1)
{
fprintf(stderr, "shmat failed\n");
exit(EXIT_FAILURE);
}
printf("\nMemory attached at %p\n", shm);
//设置共享内存
shared = (struct shared_use_st*)shm;
shared->written = 0;
while(running)//读取共享内存中的数据
{
//没有进程向共享内存定数据有数据可读取
if(shared->written != 0)
{
printf("You wrote: %s", shared->text);
sleep(rand() % 3);
//读取完数据，设置written使共享内存段可写
shared->written = 0;
//输入了end，退出循环（程序）
if(strncmp(shared->text, "end", 3) == 0)
running = 0;
}
else//有其他进程在写数据，不能读取数据
sleep(1);
}
//把共享内存从当前进程中分离
if(shmdt(shm) == -1)
{
fprintf(stderr, "shmdt failed\n");
exit(EXIT_FAILURE);
}
//删除共享内存
if(shmctl(shmid, IPC_RMID, 0) == -1)
{
fprintf(stderr, "shmctl(IPC_RMID) failed\n");
exit(EXIT_FAILURE);
}
exit(EXIT_SUCCESS);
}
读取例子：
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/shm.h>
#include "shmdata.h"
int main(void)
{
int running = 1;
void *shm = NULL;
struct shared_use_st *shared = NULL;
char buffer[BUFSIZ + 1];//用于保存输入的文本
int shmid;
//创建共享内存
shmid = shmget((key_t)1234, sizeof(struct shared_use_st), 0666|IPC_CREAT);
if(shmid == -1)
{
fprintf(stderr, "shmget failed\n");
exit(EXIT_FAILURE);
}
//将共享内存连接到当前进程的地址空间
shm = shmat(shmid, (void*)0, 0);
if(shm == (void*)-1)
{
fprintf(stderr, "shmat failed\n");
exit(EXIT_FAILURE);
}
printf("Memory attached at %p\n", shm);
//设置共享内存
shared = (struct shared_use_st*)shm;
while(running)//向共享内存中写数据
{
//数据还没有被读取，则等待数据被读取,不能向共享内存中写入文本
while(shared->written == 1)
{
sleep(1);
printf("Waiting...\n");
}
//向共享内存中写入数据
printf("Enter some text: ");
fgets(buffer, BUFSIZ, stdin);
strncpy(shared->text, buffer, TEXT_SZ);
//写完数据，设置written使共享内存段可读
shared->written = 1;
//输入了end，退出循环（程序）
if(strncmp(buffer, "end", 3) == 0)
running = 0;
}
//把共享内存从当前进程中分离
if(shmdt(shm) == -1)
{
fprintf(stderr, "shmdt failed\n");
exit(EXIT_FAILURE);
}
sleep(2);
exit(EXIT_SUCCESS);
}
套接字：
tcp服务器端：
#include <stdlib.h>
#include <sys/types.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
int main()
{
int sfp, nfp, num = 0;
struct sockaddr_in s_add,c_add;
int sin_size;
unsigned short portnum=0x8888;
char buffer[100] = {0};
printf("Hello,welcome to my server !\r\n");
//其他协议可以设置socket（AF_INET,SOCK_RAW,1...111）;
//htons()htonl()本地转网络 ntohs ntohl网络转本地
//inet_ntoa(u32) 无符号转为点分十进制
sfp = socket(AF_INET, SOCK_STREAM, 0);
if(-1 == sfp)
{
printf("socket fail ! \r\n");
return -1;
}
printf("socket ok !\r\n");
bzero(&s_add,sizeof(struct sockaddr_in));
s_add.sin_family=AF_INET;
s_add.sin_addr.s_addr=htonl(INADDR_ANY);
s_add.sin_port=htons(portnum);
if(-1 == bind(sfp,(struct sockaddr *)(&s_add), sizeof(struct sockaddr)))
{
printf("bind fail !\r\n");
return -1;
}
printf("bind ok !\r\n");
if(-1 == listen(sfp,5))
{
printf("listen fail !\r\n");
return -1;
}
printf("listen ok\r\n");
sin_size = sizeof(struct sockaddr_in);
nfp = accept(sfp, (struct sockaddr *)(&c_add), &sin_size);
if(-1 == nfp)
{
printf("accept fail !\r\n");
return -1;
}
printf("accept ok!\r\nServer start get connect from %#x : %#x\r\n",
ntohl(c_add.sin_addr.s_addr), ntohs(c_add.sin_port));
while(1)
{
memset(buffer, 0, 100);
sprintf(buffer, "hello,welcome to my server(%d) \r\n", num++);
send(nfp, buffer, strlen(buffer), 0);
usleep(500000);
}
close(nfp);
close(sfp);
return 0;
}tcp客户端：
#include <stdlib.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
int main(int argc, char **argv)
{
int cfd;
int recbyte;
int sin_size;
char buffer[1024] = {0};
struct sockaddr_in s_add, c_add;
unsigned short portnum = 0x8888;
printf("Hello,welcome to client!\r\n");
if(argc != 2)
{
printf("usage: echo ip\n");
return -1;
}
cfd = socket(AF_INET, SOCK_STREAM, 0);
if(-1 == cfd)
{
printf("socket fail ! \r\n");
return -1;
}
printf("socket ok !\r\n");
bzero(&s_add,sizeof(struct sockaddr_in));
s_add.sin_family=AF_INET;
s_add.sin_addr.s_addr= inet_addr(argv[1]);
s_add.sin_port=htons(portnum);
printf("s_addr = %#x ,port : %#x\r\n",s_add.sin_addr.s_addr,s_add.sin_port);
if(-1 == connect(cfd,(struct sockaddr *)(&s_add), sizeof(struct sockaddr)))
{
printf("connect fail !\r\n");
return -1;
}
printf("connect ok !\r\n");
while(1)
{
if(-1 == (recbyte = read(cfd, buffer, 1024)))
{
printf("read data fail !\r\n");
return -1;
}
printf("read ok\r\nREC:\r\n");
buffer[recbyte]='\0';
printf("%s\r\n",buffer);
}
close(cfd);
return 0;
}udp服务器端：
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
int main(int argc, char **argv)
{
int n;
char recvline[1024] = {0};
int sockfd;
struct sockaddr_in servaddr;
/* 创建一个UDP连接的socket */
sockfd = socket(PF_INET, SOCK_DGRAM, 0);
/* 变量servaddr清零 */
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(50001);
/* 绑定servaddr到创建的socket上 */
bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
/* 接收客户端发送的数据 */
recvfrom(sockfd, recvline, 1024, 0, NULL, NULL);
printf("%s\n", recvline);
/* 关闭socket连接 */
close(sockfd);
}udp客户端：
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
int main(int argc, char **argv)
{
int sockfd;
struct sockaddr_in servaddr;
if(argc != 2)
{
printf("usgae: ./client [ip]\n");
return -1;
}
/* 创建一个UDP的socket连接 */
sockfd = socket(PF_INET, SOCK_DGRAM, 0);
/* 变量servaddr清零 */
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(50001);
servaddr.sin_addr.s_addr = inet_addr(argv[1]);
char sendline[100];
sprintf(sendline, "Hello, world!");
/* 发送数据 */
sendto(sockfd, sendline, strlen(sendline), 0, (struct sockaddr *)&servaddr, sizeof(servaddr));
/* 关闭socket连接 */
close(sockfd);
return 1;
}线程用法：
#include <stdio.h>
#include <pthread.h>
void * thread01(void * arg)
{
int a = 0;
printf("thread01 pid is :%u\n",pthread_self());
for(;a<1000;){
a += 66;
}
printf("thread01 result is: %d,pid is:%u\n",a,pthread_self());
return NULL;
}
void * thread02(void * arg)
{
int a = 0;
printf("thread02 pid is :%u\n",pthread_self());
for(;a<1000;){
a += 66;
}
printf("thread02 result is: %d,pid is:%u\n",a,pthread_self());
return NULL;
}
int main(int args,char*argv[]){
pthread_t t1,t2;
pthread_create(&t1,NULL,thread01,NULL);
pthread_create(&t2,NULL,thread02,NULL);
pthread_join(t1,NULL);
pthread_join(t2,NULL);
return 0;
}
//编译时需要加上 -pthread