C++ 对object:：function的未定义引用

我已经在这上面呆了一段时间了，不管我如何在cygwin上编译它，我仍然无法通过它

Main.cpp

#include <iostream>
#include <istream>
#include <fstream>
#include <string>
#include <sstream>
#include <ctype.h>
#include <cstring>
#include <cstdlib>
#include "Message.h"
#include "Packet.h"
#include "main.h"
using namespace std;

void fillList(list<Message> messages, char *argv[]);
void printList(const list<Message> &messages);
int getMID(list<Message> &messages, stringstream &lines);
void create(list<Message> &messages, stringstream &lines);
bool exist(list<Message> &messages, stringstream &lines);
Message getMessage(int ID, list<Message> &messages);
void printList(const list<Message> &messages);

void fillList(list<Message> messages, char *argv[])
{
    string lines;
    ifstream files(argv[1]);
    if(files.is_open())
    {
        int delimc = 0;
        string line;
        stringstream file;
        while(getline(files,lines))
        {
            file << lines;
            if(!exist(messages, file))
                create(messages, file);
            int ID = getMID(messages, file);
            string fields[3];
            while(getline(file, line, ':'), delimc != 3)
            {
                if(delimc != 0)
                {
                    fields[delimc] = line;
                }
                delimc++;
            }
            getMessage(ID, messages).add(atoi(fields[1].c_str()), fields[2]);
            delimc = 0;
        }
    files.close();
    }
}
int getMID(list<Message> &messages, stringstream &lines)
{
    std::string line;
    getline(lines, line, ':');                  //followed standard procedure for defining string (line)
    return atoi(line.c_str());
}
void create(list<Message> &messages, stringstream &lines)
{
    messages.push_back(getMessage(getMID(messages, lines), messages));         //getID takes 2 arguments
}
bool exist(list<Message> &messages, stringstream &lines)
{
    list<Message>::iterator itr;
    for(itr = messages.begin(); itr != messages.end(); itr++)
    {
        if(itr->Message::getID() == getMID(messages, lines))                    //itr is not a pointer and if you want to point it use the correct way
            return true;
    }
    return false;
}
Message getMessage(int ID, list<Message> &messages)
{
    list<Message>::iterator itr;
    for(itr = messages.begin(); itr != messages.end(); itr++)
    {
        if(itr->Message::getID() == ID)                                     //itr is not a pointer and if you want to point it use the correct way                  
            return *itr;
    }
    //return ;                  //no need to return null, even if you want to return still you have to assign memebers of messages as null seperately
}
void printList(list<Message> &messages)
{
    list<Message>::iterator itr;

    for(itr = messages.begin(); itr != messages.end(); itr++)
    {
        cout <<  itr->Message::toString();                              //was stucked at it, you have to redesgn it in a way that you will first use add() and then packect.tostring() in order to print
    }
    cout << '\n';
}
int main(int argc, char *argv[])
{
    cout << "The Program: " << argv[0] << " was created by Newbie";
    list<Message> messages;
    fillList(messages, argv);
    printList(messages);
    return 0;
}
//input argument for the text file
//read the file with limit of 2 splitter
//split it up and create the Message with packets
//display the msg

使用cygwin编译

---

g++main.cpp Message.cpp Packet.cpp

您的cpp文件错误。您正在cpp文件中定义一个新类，

Message

，并定义其函数，而不是在头文件中的

Message

类中定义函数。您的cpp文件应如下所示：

Message::Message(int newID, list<Packet> newPackets)
{
    ID = newID;
    packets = newPackets;
}

int Message::getID()
{
    return ID;
}

void Message::setID(const int &newID)
{
    ID = newID;
}

list<Packet> Message::getPackets()
{
    return packets;
}

void Message::add(int SQN, string text)
{
    packets.push_back(Packet(SQN, text));
}

string Message::toString()
{
    ostringstream oss;
    oss << "Message " << ID;
    list<Packet>::iterator itr;
    for(itr = packets.begin(); itr != packets.end(); itr++)
    {
        oss << itr->toString();
    }
    return oss.str();
}

Message:：Message（int newID，list newPackets）
{
ID=newID；
数据包=新数据包；
}
int Message:：getID（）
{
返回ID；
}
无效消息：：setID（const int&newID）
{
ID=newID；
}
列表消息：：getPackets（）
{
返回数据包；
}
无效消息：：添加（int-SQN，字符串文本）
{
packets.push_back（Packet（SQN，text））；
}
字符串消息：：toString（）
{
ostringstream oss；
oss即使在该消息之后也是如此。cpp:15:3:error:extra-qualification'消息：：'on member'Messages'[-fppermissive]消息：：消息（int-newID，list-newPackets）^Message.cpp:21:7:error:extra-qualification'消息：：'on member'getID'[-fppermissive]int-Message：：getID（）^删除cpp文件中周围的
类消息
声明，不要在头文件中添加
消息：：
：如果我删除了类消息，我会收到此错误消息。cpp:81:1:警告：控件到达非无效函数结尾[-Wreturn type]}^Message.cpp:8:2:错误：在“private”private之前应为非限定id：^Message.cpp:12:2:错误：在“public”public之前应为非限定id：^您显然没有执行我告诉您的操作。我真的建议你读一本或两本关于C++的书。您的cpp文件中不应该有
public:
和
private:
限定符。我不知道如何进一步评论我的引用，它们的示例都有public和private限定符如果删除了类声明和限定符，那么我只会收到未声明的消息
#ifndef Message_H
#define Message_H
#include <iostream>
#include <list>
#include <ctype.h>
#include <sstream>
#include "Packet.h"
using namespace std;
class Message
{
    int ID;
    list<Packet> packets;

    public:
        Message(int ID, list<Packet> packets);
        int getID();
        list<Packet> getPackets();
        void setID(const int newID);
        void setPackets(list<Packet> newPackets);
        void add(int SQN, string text);
        string toString();
};

#endif

/tmp/ccDZ0PKH.o:main.cpp:(.text+0x1f3): undefined reference to `Message::add(int, std::string)'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x1f3): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Message::add(int, std::string)'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x4ed): undefined reference to `Message::getID()'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x4ed): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Message::getID()'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x592): undefined reference to `Message::getID()'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x592): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Message::getID()'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x63d): undefined reference to `Message::toString()'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x63d): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Message::toString()'

Message::Message(int newID, list<Packet> newPackets)
{
    ID = newID;
    packets = newPackets;
}

int Message::getID()
{
    return ID;
}

void Message::setID(const int &newID)
{
    ID = newID;
}

list<Packet> Message::getPackets()
{
    return packets;
}

void Message::add(int SQN, string text)
{
    packets.push_back(Packet(SQN, text));
}

string Message::toString()
{
    ostringstream oss;
    oss << "Message " << ID;
    list<Packet>::iterator itr;
    for(itr = packets.begin(); itr != packets.end(); itr++)
    {
        oss << itr->toString();
    }
    return oss.str();
}