简单socket套接字编程，第一试

今天又学习了socket，还是不停地出错，还是记录在这，有时间就翻出来看看（我恨那些奇怪的函数名）。

这是个简单的  客户-服务器  小列子

客户端向服务端发送一个数字字符，服务端将其转换为数字，并计算其平方，然后送给客户端。没有对输入环节进行纠错处理。

稍微改改，就可以变成多线程或多进程的服务端。

  server.c

#include<sys/types.h>#include<sys/socket.h>#include<stdio.h>#include<netinet/in.h>#include<arpa/inet.h>#include<string.h>#include<stdlib.h>int main(){    char x;    int xx;    char str[256];    int server_socktfd, client_socktfd;    int server_len, client_len;    struct sockaddr_in client_address;    struct sockaddr_in server_address;    memset(&client_address, 0, sizeof(client_address));    server_socktfd = socket(AF_INET, SOCK_STREAM, 0);    //printf("%d\n",server_socktfd);    server_address.sin_family = AF_INET;    server_address.sin_addr.s_addr = inet_addr("127.0.0.1");    server_address.sin_port = 9734;    server_len = sizeof(server_address);    bind(server_socktfd, (struct sockaddr *)&server_address, server_len);    if(listen(server_socktfd,5) < 0 ){        perror("start listen failed");        exit(1);    }    while(1) {        printf("Server waiting for connecting\n");        client_len = sizeof(client_address);        client_socktfd = accept(server_socktfd, (struct sockaddr*)&client_address, &client_len);        printf("new connect\n");        if(client_socktfd < 0){            perror("accept failed");            exit(1);        }        printf("Client %d connected\t",client_socktfd);        printf("IP:%s PORT:%d\n\n",*(inet_ntoa(client_address.sin_addr)), client_address.sin_port);

<span style="white-space:pre"></span>/**

<span style="white-space:pre"></span>这句输出很奇怪，今天的错误就出在这里，原因是类型不匹配，出现段错误，可是为什么会波及到上一个输出语句也不能输出呢，让我很无解，还以为我的accept方法的参数有问题，对了老半天，最后调试才发现错误的根源。不过，有一点好处是，让我对这段知识的影响深刻不少。所以说，当觉得某个知识点觉得难理解的时候，就写个错的程序，然后慢慢改，这也是个对知识加深了解的不错的方法。

<span style="white-space:pre"></span>*/<span style="white-space:pre"></span>        while(1) {            printf("wait calculating....\n\n");            read(client_socktfd, &x, sizeof(x));            memset(str,0,sizeof(str));            if(x!='#') {                xx = x - '0';                xx = xx*xx;                sprintf(str,"The result of %c * %c is %d", x, x, xx);            } else {                strcpy(str,"See you !");            }            write(client_socktfd, str, sizeof(str));            if(x == '#'){                printf("client %d closed\n\n",client_socktfd);                close(client_socktfd);                break;            }        }    }}

client.c

#include<sys/types.h>#include<sys/socket.h>#include<stdio.h>#include<netinet/in.h>#include<arpa/inet.h>#include<unistd.h>#include<stdlib.h>int main(){    int socktfd;    int len;    struct sockaddr_in address;    int result;    char ch;    char str[256];    socktfd = socket(AF_INET, SOCK_STREAM, 0);    //printf("%d\n",socktfd);    address.sin_family = AF_INET;    address.sin_addr.s_addr = inet_addr("127.0.0.1");    address.sin_port = 9734;    len = sizeof(address);    result = connect(socktfd, (struct sockaddr*)&address, len);    if(result == -1) {        perror("connect error");        exit(1);    } else if(result == 0) {        printf("Connecte success\n");        while(1) {            printf("input a number(quit by #):");            ch = getchar();            while(getchar()!='\n')                ;            memset(str, 0, sizeof(str));            write(socktfd, &ch, sizeof(ch));            read(socktfd, str, sizeof(str));            printf("from server: %s\n",str);            if(ch == '#') {                break;            }        }        close(socktfd);    }    exit(0);}