c++ - fatal error LNK1120 : 1 unresolved externals in c++

Question

我用c++写了一段代码:

#include<iostream>
#include<string>
#include<map>
#include<set>
#include<list>
#include<vector>
#include<fstream>

using namespace std;

#ifndef u32
typedef unsigned int u32;
#endif

vector<string> get_NodeProps(){
    vector<string> NodeProps;
    NodeProps.push_back("ObjType");
    NodeProps.push_back("Nexus");
    return NodeProps;
};
vector<string> NodeProps = get_NodeProps();

map<u32,string> create_OMSSObj_map(){
    map<u32,string> OMSSObjTypeByID1;
    OMSSObjTypeByID1.insert(pair<u32,string>(768,"storage"));
    OMSSObjTypeByID1.insert(pair<u32,string>(769,"adapter"));
    return OMSSObjTypeByID1;
};
map<u32,string> getOMSSObjTypeByID = create_OMSSObj_map();

template<typename TKey,typename TValue>
class Node{
    map<TKey,TValue> objProperties;
public:
    Node();
    Node(const map<TKey,TValue>& m);
    bool operator<(Node const& a2 ) const{
        Node const& a1 = *this;
        map<TKey,TValue>::iterator it1=a1.objProperties.begin();
        map<TKey,TValue>::iterator it2=a2.objProperties.begin();
        while(it1!=a1.objProperties.end() && it2!=a2.objProperties.end()){
            if((*it1).second < (*it2).second)
                return true;
            else if((*it1).second > (*it2).second)
                return false;
            it1++;
            it2++;
        }
    };
    map<TKey,TValue> getObjProperties();
    TValue getObjPropertyValue(TKey Key);
    void setObjProperty(TKey key,TValue Value);/*Change Value of Key if Key is available, add new key-value pair otherwise*/
    u32 removeProperty(TKey Key);
};

template<typename TKey,typename TValue>
Node<TKey,TValue>::Node(const map<TKey,TValue>& m){
    objProperties = m;
};

template<typename TKey,typename TValue>
map<TKey,TValue> Node<TKey,TValue>::getObjProperties(){
    return objProperties;
};
template<typename TKey,typename TValue>
TValue Node<TKey,TValue>::getObjPropertyValue(TKey Key){
    /*if(objProperties.count(Key)>0)
        return objProperties[Key];
    else
        return TValue();*/
    return objProperties[Key];//This work same as above(if-else)?
};
template<typename TKey,typename TValue>
void Node<TKey,TValue>::setObjProperty(TKey Key,TValue Value){
    if(!objProperties.insert(pair<TKey,TValue>(Key,Value)).second){//Key already exist: so change the Value of corresponding Key
        objProperties[Key] = Value;
    }
};
template<typename TKey,typename TValue>
u32 Node<TKey,TValue>::removeProperty(TKey Key){
    return objProperties.erase(Key);//returns 1 if erased & 0 if Key not available
};

template<typename TKey,typename TValue>
class OMSSStorage{
    set<Node<TKey,TValue>> StorageTree;
public:
    u32 addNode(Node<TKey,TValue>);
    u32 deleteNode(Node<TKey,TValue>);
    u32 contains(Node<TKey,TValue>);
    set<Node<TKey,TValue>> getStorageTree();
    u32 size();
};
template<typename TKey,typename TValue>
u32 OMSSStorage<TKey,TValue>::addNode(Node<TKey,TValue> n){
    return StorageTree.insert(n).second;
};
template<typename TKey,typename TValue>
u32 OMSSStorage<TKey,TValue>::deleteNode(Node<TKey,TValue> n){
    return StorageTree.erase(n);
};
template<typename TKey,typename TValue>
u32 OMSSStorage<TKey,TValue>::contains(Node<TKey,TValue> n){
    return(StorageTree.find(n) != StorageTree.end());
};
template<typename TKey,typename TValue>
set<Node<TKey,TValue>> OMSSStorage<TKey,TValue>::getStorageTree(){
    return(StorageTree);
};
template<typename TKey,typename TValue>
u32 OMSSStorage<TKey,TValue>::size(){
    return StorageTree.size();
};

template<typename TKey,typename TValue>
void addDCStorageObject(OMSSStorage<TKey,TValue>,string,int);
string getValueByName(string str,string name);

template<typename TKey,typename TValue>
void addDCStorageObject(OMSSStorage<TKey,TValue> tree,string StorObj,int propcount=2){
    if((int)NodeProps.size() < propcount)
        return;
    Node<string,string> n;
    for(int i=0; i<propcount ; i++){
        n.setObjProperty(NodeProps[i],getValueByName(StorObj,NodeProps[i]));
    }
    return;
};

string getValueByName(string obj,string name){
    int start,end;
    string value,temp="<",temp1="</";
    temp.append(name);
    temp1.append(name);
    start=(int)obj.find(temp);
    end=(int)obj.find(temp1);
    value=obj.substr(start,end-start);
    value=value.substr(value.find(">")+1,end-start);
    return value;
}

int main(){
    OMSSStorage<string,string> StObj;
    ifstream ifs("C:\\Users\\Public\\Documents\\share\\STORAGE.txt",ifstream::in);
    string line;
    string obj="";
    int start=0,end=0;
    while (ifs.good()){
        getline(ifs,line);
        if((line.find("<DCStorageObject>",0)) != string::npos  && start==0){
            obj.clear();
            start=1;
            end=0;
            obj.append(line);
            obj.append("\n");
        }
        else if((line.find("</DCStorageObject>",0)) != string::npos  && end==0){
            start=0;
            end=1;
            obj.append(line);
        }
        else{
            obj.append(line);
            obj.append("\n");
        }
        if(end==1){
            addDCStorageObject(StObj,obj,2);
        }
    }
    set<Node<string,string>> o = StObj.getStorageTree();
    set<Node<string,string>>::iterator its=o.begin();
    while(its!=o.end()){
        cout<<"<StorageObj>:\n";
        map<string,string> m=(*its).getObjProperties();
        map<string,string>::iterator itm=m.begin();
        while(itm!=m.end()){
            cout<<(*itm).first<<" => "<<(*itm).second<<endl;
        }
    }
    ifs.close();
    cin.get();
    return 0;
}

在编译时，这给出了链接错误。我已经尝试将类和各自的方法分离到不同的头文件中，但我仍然遇到同样的错误。错误日志作为图像文件附加

Answer 1

您只需要仔细阅读错误消息以找到缺失函数的名称(痛苦，但肯定有可能)。

在这种情况下，它表示没有 Node::Node(); 的定义——您声明了它，但从未定义过它。

编辑:我应该补充一点，我几乎没有回答这个问题——这是一个近乎完美的例子，需要将问题减少到最小 代码段来演示问题(在点，您可能不必再发帖，因为问题可能已经很明显了)。