How can I view invalid characters in a (text) file?
At the left is Notepad++ on a Windows machine. At the right is TextWrangler on a Mac machine. Notepad++ shows me what those invalid characters are, but TextWrangler just displays inverted question marks. How can I view those invalid characters (more meaningfully) on Mac?
OS: macOS High Sierra 10.13.3 Hardware: MacBook Pro Mid-2015