无法解析的外部错误在c + +中的链接列表中的代码

Question

我有一个实现代码的问题，你能帮我正确运行这段代码吗？

代码必须插入一个新客户，并显示所有客户..

我收到以下错误：

1> Source.obj：错误LNK2019：无法解析的外部符号“类 waitinglist __cdecl mylist（void）“（？mylist @@ YA？AVwaitinglist @@ XZ） reference in function _main 1> c：\ users \ mmm \ documents \ visual studio 2012 \ Projects \ ConsoleApplication141 \ Debug \ ConsoleApplication141.exe： fatal错误LNK1120：1个未解决的外部问题

这是Header.h：

#include<iostream> 
#include<string> 
using namespace std; 

class customer 
{ 
public: 
    string name; 
    int gsize; 
    int status; 
    customer* next; 

    customer(); 
    customer(string,int,int); 
}; 

class waitinglist 
{ 
public: 
    int tables; //number of occupied tables 
    int chairnum; 
    int totalcustomers; 
    customer*head,*tail; 
    waitinglist(); 
    waitinglist(int); 
    void newcustomer(string,int,int); 
    void displayall(); 
}; 

这是Source.cpp与main：

#include"Header.h" 

customer::customer() 
{ 
    name=""; 
    gsize=status=0; 
    next=NULL; 
} 

customer::customer(string name1,int gsize1,int status1) 
{ 
    name=name1; 
    gsize=gsize1; 
    status=status1; 
    next=NULL; 
} 

waitinglist::waitinglist() 
{ 
    chairnum=totalcustomers=tables=0; 
    head=tail=NULL; 
} 

waitinglist::waitinglist(int val) 
{ 
    chairnum=val; 
    totalcustomers=0; 
    tables=0; 
    head=tail=NULL; 
} 

void waitinglist::newcustomer(string name1,int gsize1 ,int status1) 
{ 
    customer*tmp= new customer; 
    if (head==NULL)   // linkedlist is empty 
    { 
     head = tail = tmp; 
     totalcustomers++; 
    } 
    else 
    { 
     tmp->next = head; 
     head = tmp; 
     totalcustomers++; 
    } 
} 

void waitinglist::displayall() 
{ 
    customer *tmp; 
    tmp = head; 
    while(tmp != NULL) 
    { 
     cout<<tmp->name <<" "<<tmp->gsize<<"-->"; 
     tmp = tmp->next; 
    } 
    cout << endl; 
} 

int main() 
{ 
    int choice; 
    string namevar=""; 
    int gsizevar=0; 
    int statusvar=0; 
    waitinglist mylist(); 
    do 
    { 
     cout<<"Note: 1 in status means{the customer not here and 2 means the customer is here.}\n"; 
     cout<<"Select your option.\n\n"; 
     cout<<"(1) Add a new Customer.\n"; 
     cout<<"(2) List all Names.\n"; 
     cout<<"(3) Quit.\n\n"; 
     cout<<"Enter your choice: -->"; 

     cin>>choice; 

     if (1 <= choice && choice <= 2) 
     { 
      switch (choice) 
      { 
      case 1: 
       mylist().newcustomer(namevar,gsizevar,statusvar); 
       break; 
      case 2: 
       mylist().displayall(); 
       break; 
      default: 
       cout << "Invalid choice. Enter again.\n\n"; 
       break; 
      } 
     } 
    } 
    while (choice != 3); 
    return 0; 
} 

Answer 1

waitinglist mylist(); 

被解释为函数声明（由于most vexing parse），它的定义你没有提供，后来，你试图打电话给它。您收到链接器错误，因为找不到该定义。

在main每个mylist occurence后删除括号：

waitinglist mylist;        // default-construct mylist 
... 
mylist.newcustomer(namevar,gsizevar,statusvar); // use mylist object 
... 
mylist.displayall();