Can You Directly Jump to a Specific Line in a Text File Using C fstream?

Seeking a Specific Line in Text File with C

With the fstream library in C , it becomes convenient to read and write to text files. However, directly navigating to a specific line can be challenging. This question explores a potential solution to this problem.

Problem:

If a text file is opened using fstream, is there a straightforward way to jump to a particular line, such as line 8?

Answer:

Although fstream provides a way to set the seek pointer of the file, it directly does not allow jumping to a specific line. A practical approach is to loop through the file, ignoring all lines until the desired line is reached. Here's how it can be achieved:

<code class="cpp">std::fstream& GotoLine(std::fstream& file, unsigned int num) {
    file.seekg(std::ios::beg);
    for (int i = 0; i < num - 1; ++i) {
        file.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
    }
    return file;
}</code>

This function takes the file and the line number that it should seek to and returns the file object.

Example:

Consider a text file with the following content:

1
2
3
4
5
6
7
8
9
10

The following C program demonstrates how to use the GotoLine function:

<code class="cpp">int main() {
    using namespace std;
    fstream file("bla.txt");

    GotoLine(file, 8);

    string line8;
    file >> line8;

    cout << line8;
    cin.get();
    return 0;
}</code>

Output:

8

In this example, the program reads the eighth line of the text file and prints the content, which is "8".

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