How to Jump to a Specific Line in a Text File Using C ?

Navigating Text File Lines in C

When working with text files using C , you may encounter the need to jump to a specific line. While there's no direct method provided by C for this purpose, you can achieve it by looping through the file until you reach the desired line.

Looping to Specific Line

The solution involves using a loop to count lines until you reach the target line number. This technique is demonstrated in the code snippet below:

<code class="cpp">#include <fstream>
#include <limits>

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>

The GotoLine function sets the seek pointer of the file stream to the beginning of the specified num line.

Testing the Code

To illustrate this technique, consider a text file with the following content:

1
2
3
4
5
6
7
8
9
10

The following test program demonstrates how to jump to line 8 and read the contents:

<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

By implementing the looping approach, you can easily navigate to any specific line in a text file and access its contents in C .

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