我正在开发一个必须在不同机器上工作的独特客户端。在每台机器中,服务器都在不同的 IP 地址中运行,但该地址是已知的。
我不想每次运行时都告诉客户端哪个是IP,所以我想在编译时告诉它。
问题是当编译时g++ -DHOSTNAME=127.0.0.1
(也尝试使用双引号)编译器说:
error: too many decimal points in number
./include/Client.h:18:25: note: in expansion of macro ‘HOSTNAME’
我也使用本地主机尝试过。
error: ‘localhost’ was not declared in this scope
./include/Client.h:18:25: note: in expansion of macro ‘HOSTNAME’
还尝试使用互联网上找到的一些东西。
#define XSTR(x) STR(x)
#define STR(x)
编译错误:
./src/BSCClient.cpp:15:45: note: #pragma message: HOSTNAME:
#pragma message("HOSTNAME: " XSTR(HOSTNAME))
./src/BSCClient.cpp:16:39: error: too few arguments to function ‘hostent* gethostbyname(const char*)’
server = gethostbyname(XSTR(HOSTNAME));
此时,我认为宏可能不是处理此问题的正确方法,但我不知道该怎么做。
如果有人对此有任何参考,我将不胜感激。
编辑:
这些是代码。
客户端.h:
#ifndef __CLIENT_HH__
#define __CLIENT_HH__
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <string>
#include <iostream>
using namespace std;
#define HOSTNAME 127.0.0.1
#define MAX_MESSAGE_LENGTH 10
class Client {
private:
string client_name;
int sockfd, portno;
struct sockaddr_in serv_addr;
struct hostent *server;
error(const char *msg);
public:
BSCClient (string name, int port);
void identifyme();
void sendData (string data);
string recvData ();
void closeSocket();
};
#endif
客户端.cpp
#include "BSCClient.h"
#include <stdlib.h>
#include <time.h>
void BSCClient::error(const char *msg)
{
perror(msg);
exit(0);
}
Client::Client(string name, int port)
{
sockfd = socket(AF_INET, SOCK_STREAM, 0);
portno = port;
client_name = name;
if (sockfd < 0)
error("ERROR opening socket");
server = gethostbyname(HOSTNAME);
if (server == NULL) {
fprintf(stderr,"ERROR, no such host\n");
exit(0);
}
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
bcopy((char *)server->h_addr,
(char *)&serv_addr.sin_addr.s_addr,
server->h_length);
serv_addr.sin_port = htons(portno);
if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
error("ERROR connecting");
sendData(client_name);
}
void Client::identifyme() {
FILE *fp;
fp = popen("id -gn", "r");
char text[6];
fscanf(fp, "%s", text);
pclose(fp);
string data(text);
sendData(data);
}
void Client::sendData (string data) {
const char *sdata = data.c_str();
int n;
n = write(sockfd, sdata, strlen(sdata));
if (n < 0)
error("ERROR writing to socket");
}
string Client::recvData () {
int n;
int bytes;
char *longitud = new char[MAX_MESSAGE_LENGTH+1];
n = read(sockfd, longitud, MAX_MESSAGE_LENGTH);
if (n < 0) {
error("ERROR recieving size of output");
}
bytes=atoi(longitud);
//Para forzar el fin del string (ya que al imprimir el string hay veces que muestra caracteres de más)
longitud[MAX_MESSAGE_LENGTH]='\0';
char *data = new char[bytes];
n = read(sockfd, data, bytes);
if (n < 0)
error("ERROR reading output");
string ret(data);
return ret;
}
void Client::closeSocket() {
close(sockfd);
}