网络编程 -- 基于客户端 - 服务端的计算器

 服务端从客户端获得多个数字和运算符信息，服务端受到数字后对其进行加减乘运算，然后把结果传回客户端。程序如下， 已注释。

• 服务端程序如下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#define BUF_SIZE 1024
#define OPSZ 4
void error_handling(char *message);
int calculate(int opnum, int opnds[], char oprator);
int main(int argc, char *argv[])
{
    int serv_sock, clnt_sock;
    char opinfo[BUF_SIZE];
    int result, opnd_cnt, i;
    int recv_cnt, recv_len;
    struct sockaddr_in serv_adr, clnt_adr;
    socklen_t clnt_adr_sz;
    if (argc != 2)
    {
        printf("Usage : %s <port>\n", argv[0]);
        exit(1);
    }

    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if (serv_sock == -1)
        error_handling("socket() error");

    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_adr.sin_port = htons(atoi(argv[1]));

    if (bind(serv_sock, (struct sockaddr *)&serv_adr, sizeof(serv_adr)) == -1)
        error_handling("bind() error");
    if (listen(serv_sock, 5) == -1)
        error_handling("listen() error");
    clnt_adr_sz = sizeof(clnt_adr);
    for (int i = 0; i < 5; i++)
    {
        opnd_cnt = 0;
        clnt_sock = accept(serv_sock, (struct sockaddr *)&clnt_adr, &clnt_adr_sz);
        read(clnt_sock, &opnd_cnt, 1);

        recv_len = 0;
        while ((opnd_cnt * OPSZ + 1) > recv_len)
        {
            recv_cnt = read(clnt_sock, &opinfo[recv_len], BUF_SIZE - 1);
            recv_len += recv_cnt;
        }
        result = calculate(opnd_cnt, (int *)opinfo, opinfo[recv_len - 1]);
        write(clnt_sock, (char *)&result, sizeof(result));
        close(clnt_sock);
    }
    close(serv_sock);
    return 0;
}
int calculate(int opnum, int opnds[], char op)
{
    int result = opnds[0], i;
    switch (op)
    {
    case '+':
        for (i = 1; i < opnum; i++)
            result += opnds[i];
        break;
    case '-':
        for (i = 1; i < opnum; i++)
            result -= opnds[i];
        break;
    case '*':
        for (i = 1; i < opnum; i++)
            result *= opnds[i];
        break;
    }
    return result;
}
void error_handling(char *message)
{
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

• 客户端程序如下

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#define BUF_SIZE 1024
#define RLT_SIZE 4 //字节大小数
#define OPSZ 4
void error_handling(char *message);

int main(int argc, char *argv[])
{
    int sock;
    char opmsg[BUF_SIZE];
    int result, opnd_cnt, i;
    struct sockaddr_in serv_adr;
    if (argc != 3)
    {
        printf("Usage : %s <IP> <port>\n", argv[0]);
        exit(1);
    }

    sock = socket(PF_INET, SOCK_STREAM, 0);
    if (sock == -1)
        error_handling("socket() error");

    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = inet_addr(argv[1]);
    serv_adr.sin_port = htons(atoi(argv[2]));

    if (connect(sock, (struct sockaddr *)&serv_adr, sizeof(serv_adr)) == -1)
        error_handling("connect() error!");
    else
        puts("Connected...........");

    fputs("Operand count: ", stdout);
    scanf("%d", &opnd_cnt);
    opmsg[0] = (char)opnd_cnt;

    for (i = 0; i < opnd_cnt; i++)
    {
        printf("Operand %d: ", i + 1);
        scanf("%d", (int *)&opmsg[i * OPSZ + 1]);
    }
    fgetc(stdin);
    fputs("Operator: ", stdout);
    scanf("%c", &opmsg[opnd_cnt * OPSZ + 1]);
    write(sock, opmsg, opnd_cnt * OPSZ + 2);
    read(sock, &result, RLT_SIZE);

    printf("Operation result: %d \n", result);
    close(sock);
    return 0;
}

void error_handling(char *message)
{
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

• 运行结果