SEEKG()

This is used to reposition the get pointer (read pointer) within a file stream. It allows programmers to move the pointer to a specific location in the file, enabling precise control over where data is read from. It is particularly useful when you need to skip a certain number of bytes, revisit previously read sections, or access data at a known offset. By combining seekg() with the tellg() function, which reports the current position of the get pointer, developers can implement efficient file navigation and random access operations, making it an essential tool for reading structured or binary files.

// Move get pointer to an absolute position
istream& seekg(streampos pos);

// Move get pointer relative to a specific direction
istream& seekg(streamoff off, ios_base::seekdir dir);

 * streampos pos — an absolute position in the file from the beginning.
 * streamoff off — a byte offset.
 * ios_base::seekdir dir — the reference point for the offset; can be:
    - ios::beg — beginning of the file
    - ios::cur — current position
    - ios::end — end of the file

#include <iostream>
#include <fstream>

using namespace std;

int main() {
    ifstream file("example.txt");

    if (file.is_open()) {
        // Move the read pointer to the 5th byte from the beginning
        file.seekg(5);

        // Read from the new position
        char ch;
        file.get(ch);
        cout << "Character at position 5: " << ch << endl;

        file.close();
    } else {
        cout << "Unable to open file!" << endl;
    }

    return 0;
}

 * seekg(5) moves the read pointer to the 5th byte, and then get(ch) reads
   the character at that position.

EXAMPLE

#include <iostream>
#include <fstream>
using namespace std;

int main() {
    ifstream file("data.txt");

    if (file) {
        // Read and print the first 10 characters
        cout << "First 10 characters: ";
        for (int i = 0; i < 10; i++) {
            char ch;
            file.get(ch);    // Use get(ch) to read one character and it by default moves the file pointer forward
            cout << ch;      // print the read character
        }
        cout << endl;

        // Move the file pointer to the 5th character (index 4)
        file.seekg(4);

        // Read and print 5 characters from that position
        cout << "Characters from position 4: ";
        for (int i = 0; i <= 4; i++) {
            char ch;
            file.get(ch);
            cout << ch; // print the read character
        }
        cout << endl;

        file.close();
    } else {
        cout << "Could not open the file." << endl;
    }

    return 0;
}

 * INPUT FILE: data.txt
    abcdefghijklmnopqrstuvwxyz
 * OUTPUT:
    First 10 characters: abcdefghij
    Characters from position 4: efghi

WORD EXTRACTION

#include <iostream>
#include <fstream>
using namespace std;

int main() {
    ifstream file("content.txt");

    if (file) {
        // Read and print the first 15 characters
        cout << "First 15 characters: ";
        for(int i = 0; i < 15; i++){
            char ch;
            file.get(ch);
            cout << ch;
        }

        cout << endl;

        // Move the file pointer to the 10th character (index 9)
        file.seekg(9);

        // Read and print 8 characters from that position
        cout << "Characters from position 9: ";
        
        // Write your code here
        for(int i = 0; i < 8; i++){
            char ch;
            file.get(ch);
            cout << ch;
        }

        cout << endl;

        file.close();
    } else {
        cout << "Could not open the file." << endl;
    }

    return 0;
}

 * INPUT FILE: content.txt
    12345678901234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ
 * OUTPUT:
    First 15 characters: 123456789012345
    Characters from position 9: 01234567