C语言最简单的服务器和客户端程序

服务器

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>

#define BACKLOG 5

int main(int argc, char *argv[])
{
	int fd, newfd, ret;
	char buf[BUFSIZ] = {}; //BUFSIZ 8142
	struct sockaddr_in addr;
	
	if(argc < 3){
		fprintf(stderr, "%s<addr><port>\n", argv[0]);
		exit(0);
	}

	/*创建套接字*/
	fd = socket(AF_INET, SOCK_STREAM, 0);
	if(fd < 0){
		perror("socket");
		exit(0);
	}
	addr.sin_family = AF_INET;
	addr.sin_port = htons( atoi(argv[2]) );
	if ( inet_aton(argv[1], &addr.sin_addr) == 0) {
		fprintf(stderr, "Invalid address\n");
		exit(EXIT_FAILURE);
	}

	/*绑定通信结构体*/
	if(bind(fd, (struct sockaddr *)&addr, sizeof(addr) ) == -1){
		perror("bind");
		exit(0);
	}
	/*设置套接字为监听模式*/
	if(listen(fd, BACKLOG) == -1){
		perror("listen");
		exit(0);
	}
	/*接受客户端的连接请求，生成新的用于和客户端通信的套接字*/
	newfd = accept(fd, NULL, NULL);
	if(newfd < 0){
		perror("accept");
		exit(0);
	}
	while(1){
		memset(buf, 0, BUFSIZ);
		ret = read(newfd, buf, BUFSIZ);
		if(ret < 0)
		{
			perror("read");
			exit(0);
		}
		else if(ret == 0)
			break;
		else
			printf("buf = %s\n", buf);
	}
	close(newfd);
	close(fd);
	return 0;
}

客户端

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>

#define BACKLOG 5

int main(int argc, char *argv[])
{
	int fd;
	struct sockaddr_in addr;
	char buf[BUFSIZ] = {};

	if(argc < 3){
		fprintf(stderr, "%s<addr><port>\n", argv[0]);
		exit(0);
	}

	/*创建套接字*/
	fd = socket(AF_INET, SOCK_STREAM, 0);
	if(fd < 0){
		perror("socket");
		exit(0);
	}

	addr.sin_family = AF_INET;
	addr.sin_port = htons( atoi(argv[2]) );
	if ( inet_aton(argv[1], &addr.sin_addr) == 0) {
		fprintf(stderr, "Invalid address\n");
		exit(EXIT_FAILURE);
	}

	/*向服务端发起连接请求*/
	if(connect(fd, (struct sockaddr *)&addr, sizeof(addr) ) == -1){
		perror("connect");
		exit(0);
	}
	while(1){
		printf("Input->");
		fgets(buf, BUFSIZ, stdin);
		write(fd, buf, strlen(buf) );
	}
	close(fd);
	return 0;
}

验证方式

通过gcc生成可执行文件后，先运行服务器（./sever.exe 0 8888），这里的0指的是IP地址0.0.0.0，8888指定的端口；客户端运行（./client.exe 127.0.0.1 8888），这里用127.0.0.1是回环地址，8888是端口号。