How to Rewind a File Pointer in Golang?

Rewinding File Pointer in Golang

In Golang, one may encounter a scenario where it's necessary to rewind the file pointer for reading a file multiple times. There are two main options to achieve this:

1. Seeking to the Beginning of the File:

This method is considered the simplest and efficient approach. By calling the File.Seek function with the arguments (0, 0) or (0, io.SeekStart), you can set the pointer to the start of the file:

This approach ensures fast and effortless rewinding without the need to close and reopen the file, making it suitable for scenarios where you need to read different sections of a file multiple times.

2. Closing and Reopening the File:

Alternatively, you can choose to close the file and open it again before the second reading. This method has the advantage of creating a new file object and file pointer at the start of the file. However, it's important to note that file opening can be relatively slower compared to seeking, especially for large files. Therefore, this approach is less recommended for scenarios where performance is critical.

Using File as an io.Reader:

In Golang, the *os.File type implements the io.Reader interface. This means that you can directly use a *os.File as an io.Reader without the need for any conversion or intermediary readers. Therefore, the code snippet you provided is correct and works as intended:

Using a *os.File as an io.Reader is efficient and convenient, as it eliminates the need for additional readers and simplifies your code.

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