ifstream不能循环工作

Question

I just started programming using C++. I face some problem during execution of ifstream in loop.

do  
{  
    system("cls");  
    inFile.open ("Account_Details.txt");  
    while (!inFile.eof())  
    {  
         getline (inFile, line);  
         cout << line << endl;  
    }  
         inFile.close();  
         cin.ignore(100, '\n');  
         cin >> choice;  
}  
while (choice != '1' && choice != '2');  

This is part of my code. When the loop run, it doesnt show data in the txt file.
Thanks for any help. ^^

Answer 1

在infile.close（）之后添加infile.clear（）-关闭不会清除eof位

Answer 2

There is a chance that the file doesn't exist. If that's the case, it will create an empty file. Check the path of the file.

Answer 3

I have been writing C++ code for close to 10 years. During that time I have learnt how to use C++ in a way that minimizes the number of errors (bugs) I create. Probably some will disagree with me, but I would recommend you to only use for and while to do looping. Never do-while. Learn these two well and you will be able to loop successfully any time you want.

To illustrate my technique, I have taken the liberty to rewrite your code using my style. It has complete error checking, uses a while loop with read-ahead, some C++0x, and simplified stream handling:

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <string>

int main(int argc, char** argv)
{
   // check program arguments
   if (argc<2) {
      std::cerr << "Usage: " << argv[0] << " file" << std::endl;
      return EXIT_FAILURE;
   }

   // check file can be opened
   std::ifstream infile(argv[1]);
   if (!infile) {
      std::cerr << "Failed to read " << argv[1] << std::endl;
      return EXIT_FAILURE;
   }

   std::string input;

   // read-ahead
   std::getline(std::cin, input);

   while (input!="q" && input!="quit" && input!="exit") {
      //system("cls");

      // print contents of file by streaming its read buffer
      std::cout << infile.rdbuf();

      // read file again
      infile = std::ifstream(argv[1]);

      // finally, read again to match read-ahead
      std::getline(std::cin, input);
   }
}

Save to main.cpp , compile to print.exe and run with print.exe main.cpp . Good luck with learning C++!