How do I toggle, uppercase, or lowercase text using motion commands in Vim?

Explanation

Vim has three case-change operators that work like any other operator — you can combine them with motions, text objects, or double them to act on the whole line. This lets you perform case transformations without entering visual mode.

How it works

• g~{motion} — toggle case (upper↔lower) over a motion
• gU{motion} — convert to uppercase over a motion
• gu{motion} — convert to lowercase over a motion
• Doubling the command applies to the entire current line: g~~, gUU, guu

Example

Given:

Hello World

Tips

• Combine with any text object: gUi" uppercases the text inside quotes, gu2w lowercases the next two words
• In visual mode, U, u, and ~ do the same thing as gU, gu, and g~ on the selection
• Use with iw, is, ip text objects for word, sentence, or paragraph transforms
• gUgU is a (less common) equivalent to gUU