seekg tellg end of line

I have to read lines from an extern text file and need the 1. character of so开发者_开发技巧me lines.

Is there a function, which can tell me, in which line the pointer is and an other function, which can set the pointer to the begin of line x?

I have to jump to lines before and after the current position.

There is no such function i think. You will have to implement this functionality yourself using getline() probably, or scan the file for endline characters (\n) one character at a time and store just the one character after this one.

You may find a vector (vector<size_t> probably) helpful to store the offsets of line starts, this way you might be able to jump in the file in a line-based way. But haven't tried this, so it may not work.

You may ake a look at ifstream to read your file in a stream, then use getline() to get each line in a std::string.

Doing so, you can easily iterate trough the lines and grab the characters you need.

Here is an example (taken from here):

// reading a text file
#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main () {
  string line;
  ifstream myfile ("example.txt");
  if (myfile.is_open())
  {
    while (! myfile.eof() )
    {
      getline (myfile,line);
      cout << line << endl; // Here instead of displaying the string
      // you probably want to get the first character, aka. line[0]
    }
    myfile.close();
  }

  else cout << "Unable to open file"; 

  return 0;
}