我正在尝试编写一个从文本文件中的脚本读取的冒险游戏。该程序编译并运行，但它不读取我的.txt文件，我无法弄清楚出了什么问题。
在我的GetAreaInfo函数中
行“fin.seekg（NULL，IOS :: BEG）;”显示警告说
“main.cpp：92：28：警告：将NULL传递给'std :: basic_istream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_istream＆lt; _CharT，_Traits＆gt; :: seekg（std：）的非指针参数1 ：basic_istream＆lt; _CharT，_Traits＆gt; :: off_type，std :: ios_base :: seekdir）[with _CharT = char; _Traits = std :: char_traits; std :: basic_istream＆lt; _CharT，_Traits＆gt; :: off_type = long int; std： ：ios_base :: seekdir = std :: _ Ios_Seekdir]'[ - Wconversion-null]“
我无法弄清楚如何让它消失，但我相信这是问题所在。任何帮助将不胜感激
[代码]
//file libraries
#include <iostream>
#include <fstream>
#include <string>
#include <windows.h>
using namespace std;
#define GAMEFILE "world.txt"//read in for the world data
#define CONTINUE 1
#define QUIT 0
//user libraries
struct tArea{//structure that holds the info for the main area
string strCurrentArea;//name of current area
string strDescription;//description of current area
string strNorth;//name of area to the north
string strSouth;//name of area to the south
string strEast;//name of area to the east
string strWest;//name of area to the west
};
//global constants
//function prototypes
void DisplayArea(tArea &area);
void GetAreaInfo(ifstream&,tArea &area);
void Move(ifstream&,tArea &area,string);
int Input(ifstream&,tArea &area);
//execution
int main(){
ifstream fin;//pointer that opens and reads from file
tArea area;//area structure data
fin.open(GAMEFILE);//
if(fin.fail()){
cout<<"UNABLE TO FIND GAME FILE\n";
return -1;
}
fin>>area.strCurrentArea>>area.strCurrentArea;//reads in the start point for the game
GetAreaInfo(fin,area);//calls function to receive info from the file
DisplayArea(area);//calls function to display the area to the user
while(1){//main game loop
if(Input(fin,area)==QUIT){//if user enters quit, game ends
break;
}
}
fin.close();//closes file
Sleep(1000);//1 second delay before ending
return 0;
}
/**********************************************************/
//*****************DisplayArea*****************************/
//******Function is called to display area description*****/
/**********************************************************/
void DisplayArea(tArea &area)
{
cout<<area.strDescription<<endl<<endl;
}
/**********************************************************/
//*****************GetAreaInfo*****************************/
//******Function is called to read in the area*************/
//************information from the file********************/
/**********************************************************/
void GetAreaInfo(ifstream &fin,tArea &area){
string strTemp="";
string strTemp2="";//temporary for reading in info
string strArea="<"+area.strCurrentArea+">";//looks for the room name in brackets to find easier i.e instead of main it reads in <main>
fin.seekg(NULL,ios::beg);//starts the header search from the beginning of the file
fin.clear();//allows the file to be read through multiple times
while(getline(fin, strTemp, '\n')){//while loop reads file til it finds the correct area heading
if(strTemp==strArea){
getline(fin, area.strDescription, '*');//if it finds the correct area heading, it reads its info
// Read past the direction blocks (I.E. <north>) and store the room name for that direction
fin>>strTemp>>area.strNorth;
fin>>strTemp>>area.strEast;
fin>>strTemp>>area.strSouth;
fin>>strTemp>>area.strWest;//it then read in the surrounding area titles by skipping their <area> descriptors
return;
}
}
}
/**********************************************************/
//*********************Move********************************/
//******Function is called to move through the*************/
//****game if there is an area in that direction***********/
/**********************************************************/
void Move(ifstream &fin,tArea &area, string strArea){
if(strArea=="None"){//detects if there is no area in the direction inputted
cout<<"You are unable to travel that way\n";//displays error message and returns the function
return;
}
else{
area.strCurrentArea=strArea;// Sets the current area to the new one
GetAreaInfo(fin, area); // Passes in the file pointer so the new area data is read
DisplayArea(area);// Displays current area
}
}
/**********************************************************/
//*********************Input*******************************/
//******Main game mechanic feature. Receives **************/
//****user input and reacts to it accordingly to **********/
//*******progress through the game*************************/
/**********************************************************/
int Input(ifstream &fin, tArea &area){
string strInput="";//holds user input
cout<<endl<<":";//displays prompt
cin>>strInput;//reads in the user input
if(strInput=="look"){
DisplayArea(area);//calls function to give current area description
}
else if(strInput=="north"){
Move(fin,area,area.strNorth);//calls function to move north if possible
}
else if(strInput=="east"){
Move(fin,area,area.strEast);//calls function to move east if possible
}
else if(strInput=="west"){
Move(fin,area,area.strWest);//calls function to move west is possible
}
else if(strInput=="south"){//calls function to move south if possible
Move(fin,area,area.strSouth);
}
else if(strInput=="help"||strInput=="?"){//displays commands to user
cout<<"Commands: north east west south look quit help\n";
}
else if(strInput=="quit"){//ends game
cout<<"Quit game?\n";
return QUIT;
}
else{//displays when invalid input is received
cout<<"Invalid input\n";
}
return CONTINUE;
}
答案 0 :(得分：0)
iostream::seekg具有以下签名：
istream& seekg (streampos pos); istream& seekg (streamoff off, ios_base::seekdir way); NULL是一个空指针常量。
你可能想写：
fin.seekg(0, ios::beg);
或简单地说：
fin.seekg(0);
这两项都将从一开始就开始寻求。