HOW to get the current position within the file

To get the current position within a file in C++, you can use the tellg() function for input files and tellp() function for output files. These functions return the current position in the stream as a streampos object. Here's an example:

#include <fstream>
#include <iostream>

int main() {
    std::ifstream input_file("example.txt");
    if (!input_file.is_open()) {
        std::cerr << "Failed to open file\n";
        return 1;
    }

    // Get current position in file
    std::streampos pos = input_file.tellg();
    std::cout << "Current position: " << pos << '\n';

    // Do some reading and move position
    char c;
    input_file >> c;
    pos = input_file.tellg();
    std::cout << "New position: " << pos << '\n';

    input_file.close();
    return 0;
}

This program opens a file "example.txt", gets the current position using tellg(), reads one character from the file, and gets the new position again. The output will show the two positions in the file.