how to know the file extension from byte array in golang

To determine the file extension from a byte array in Go, you can follow these steps:

1. Convert the byte array to a string.
2. Use the path package to extract the file extension from the string.
3. Handle cases where the file extension may not be present.

Here's an example implementation:

package main

import (
    "fmt"
    "path"
)

func getFileExtension(data []byte) string {
    // Convert the byte array to a string
    str := string(data)

    // Extract the file extension using the path package
    ext := path.Ext(str)

    // Handle cases where the file extension may not be present
    if ext == "" {
        return "No file extension found"
    }

    return ext
}

func main() {
    // Example byte array
    data := []byte{0x50, 0x4B, 0x03, 0x04}

    // Get the file extension
    extension := getFileExtension(data)

    fmt.Println("File extension:", extension)
}

Explanation of each step:

1. Convert the byte array to a string:

2. We use the string() function to convert the byte array data to a string str.

3. Use the path package to extract the file extension from the string:

4. We import the path package to access the Ext() function.
5. The Ext() function returns the file extension from a given string.

6. We pass the str string to the Ext() function to extract the file extension ext.

7. Handle cases where the file extension may not be present:

8. We check if the ext variable is an empty string, indicating that no file extension was found.
9. If the ext is empty, we return the message "No file extension found".
10. Otherwise, we return the extracted file extension.

In the example above, we use the byte array {0x50, 0x4B, 0x03, 0x04} as an example input. You can replace it with your own byte array to test the function.

I hope this helps! Let me know if you have any further questions.