How to Rewind a Go *os.File Pointer After Writing to Read Data From the Beginning?

Seek Your File Pointer to Read Data Written to the Same *os.File in Go

When working with files in Go using the *os.File pointer, it's important to understand how file pointers work. The file pointer keeps track of the current position in the file. When writing to a file, the file pointer automatically advances to the end of the written data.

In your case, you want to write and then read data from the same *os.File pointer. However, after the write loop, the file pointer is positioned at the end of the file, causing you to read nothing when trying to read from the start of the file.

To solve this issue, you need to "rewind" the file pointer to the beginning of the file before attempting to read from it. This can be achieved using the Seek function on the *os.File pointer.

Here's how to do it:

_, err := f.Seek(0, 0)
if err != nil {
    fmt.Println("Error", err)
}

The code above seeks to the beginning of the file, passing in the arguments 0 for the offset and 0 for the starting position (beginning of the file). Now, you can read from the file without encountering the io.EOF error.

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