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c++ - C++ 错误无法从指针转换为指针

问题描述

我被要求编写一个从文件中读取数据并将其数据输入双向链表的函数。但是每次我尝试运行该程序时，都会显示以下编译错误：

[Error] could not convert 'I1' from 'opening(World&)::Individual*' to 'Individual'
[Error] could not convert 'I2' from 'opening(World&)::Individual*' to 'Individual'

这是文件的内容：

FName1#LName1#Age1#male#University1,FName2#LName2#Age2#male#University2
FName1#LName1#Age1#male#University1,FName3#LName3#Age3#male#University3
FName7#LName7#Age7#female#University7,FName1#LName1#Age1#male#University1
FName7#LName7#Age7#female#University7,FName2#LName2#Age2#male#University2
FName6#LName6#Age6#female#University6,FName7#LName7#Age7#female#University7
FName4#LName4#Age4#male#University4,FName6#LName6#Age6#female#University6
FName4#LName4#Age4#male#University4,FName5#LName5#Age5#male#University5
FName5#LName5#Age5#male#University5,FName6#LName6#Age6#female#University6

那是我的代码：

#include <iostream>
#include <fstream>
#include <string.h>
#include <string.h>

using namespace std;

 struct Friend;
 struct World ;
 struct Individual;

struct Friend{
    Individual *self;
    Friend *next;
};

struct Individual{
    string FirstName,
    LastName,
    University;
    int Age;
    bool gender;
    Friend *myFriends;    // used as an adjacency list to enumerate all friends
    Individual *next;     // usedfor the doubly linked list denoted by World
    Individual *previous; // used for the doubly linked list denoted by World
};


struct World {
    Individual *Head, *Tail;
};
 World * InitializeList()
{
    return NULL;
}



void InsertInWorld(World & network, Individual I) {

    Individual* tmp = new Individual;
    if (tmp == NULL)
    {
        exit(1);
    }
    tmp->FirstName = I.FirstName;
    tmp->LastName = I.LastName;
    tmp->University = I.University;
    tmp->Age = I.Age;
    tmp->gender = I.gender;
    tmp->myFriends->next = NULL;
    tmp->myFriends->self = NULL;
    tmp->next = NULL;
    tmp->previous = NULL;

    if (network.Head == NULL || network.Tail==NULL) {
        network.Head = tmp;
        network.Tail = tmp;
        return;
    }
    else
    {
        tmp->next = network.Head;
        network.Head->previous = tmp;
        network.Head = tmp;
        return;
    }

}


void DisplayWorld(World network)
{
    Individual *cur = network.Head;
    
    while(cur!=NULL)
    {
        cout<<cur->FirstName<<" "<<cur->LastName<<endl;
        cur=cur->next;
    }
    
    cout<<endl;
}

void opening (World &network )
{
    struct Individual{
    string FirstName,
    LastName,
    University;
    string Age;
    string gender;
    Friend* myFriends;
    Individual* next;
    Individual* previous;
    
};

struct World {
    Individual *Head, *Tail;
};

    
    Individual *I1 ;
    Individual *I2 ;
    I1 = new Individual;
    I2 = new Individual;
    Individual *cur;
    
//  cur = network->Head;
    
    
    
 ifstream connections;
 connections.open("conn.txt");
  while (   getline(connections, I1->FirstName,'#')  && getline(connections, I1->LastName, '#')  && getline(connections, I1->University,'#')  && getline(connections,I1->Age,'#')  && getline(connections,I1->gender,',') && getline(connections, I2->FirstName,'#')  && getline(connections, I2->LastName, '#')  && getline(connections, I2->University,'#')  && getline(connections, I2->Age,'#')  && getline(connections, I2->gender,'\n')) 
    {
   
        
        InsertInWorld(network, I1);
        InsertInWorld(network, I2);
        
    }
    
    
    
}


    
    
    int main()
    {

        World network;
        Individual *I1=new Individual;
        network.Head=NULL;
        network.Tail=NULL;
        opening(network);
        DisplayWorld(network);
        
        return 0;
    }

如果有人可以帮助我解决这个编译错误。谢谢你。

标签： c++pointersstruct

解决方案

有两个类似struct的s叫做Individual。一个在文件范围内，另一个在opening(). 由于它们是两种不同的类型，因此您无法隐式转换指向它们的指针（当您学习时，几乎可以保证您做错了什么）。

但是，正如@IgorTandetnik 在评论中指出的那样，错误与此无关，请注意：

could not convert ... from '...Individual*' to 'Individual'
                                         ^                ^

第二种类型不是指针，因此您需要取消引用它：

InsertInWorld(network, *I1);

尽管在这种情况下您可能想要做的是传递参考：

void InsertInWorld(World & network, Individual & I) {

也可能是const一个。

代码中还有其他问题。我建议您将其发布在代码审查堆栈交换站点中。

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