How to abort when the number of rows in the file is less than the number of rows read in the target-CodePudding

Now I have a txt file like this:

One loop of this file is 7 lines, and the second line of the 7 lines is a blank line. My file has a total of 5 loops , but when my code is set to read 10 loops, the code will not report an error, how should I modify the code to report an error at the end of the file, pay attention to my text file a blank line appears.

#include<fstream>
#include<string>
int main()
{

  std::ifstream get_in("tst.txt", std::ios :: in );

  for ( int loop=0;loop<10;loop   )
  {
    std::string line;

    for ( int i=0;i<7;i   )
    {
      getline(get_in, line);
    }
  }
return 0;
}

This is a simplified example of my code, I want it to error out when the text is not enough for the number of rows I want to read, instead of running normally.

CodePudding user response：

Check the input stream's eof bit, which can be done by directly accessing it get_in.eofbit or by using the eof() function, get_in.eof().

I would recommend using the eof() function.

I am not sure what you are doing with your code, but here is a simple to understand modification of your code as a demonstration:

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

int main()
{

  std::ifstream get_in("tst.txt", std::ios :: in );
  std::string line;
  for ( int loop=0;loop<10;loop   )
  {
    if(get_in.eof()) { std::cout << "EOF"; break; }
    for ( int i=0;i<7;i   )
    {
      std::getline(get_in, line);
      if(get_in.eof()) break;
      std::cout << line << std::endl;
    }
  }
return 0;
}