Refactor code by simplifying it

[alexandear]

The PR refactors code:

• Change to use i++ instead of i = i + 1.
• Use fmt.Fprint because fmt.Fprintf is not needed.
• Add a whitespace between // and a sentence.
• Remove //------------------------------------------------------------------- lines.
• Use switch instead of long if-else-if to increase readability.
• Use s != "" instead of len(s) > 0 because the first is more idiomatic.
• Combine func parameters.