What does the 'k' prefix indicate in Apple's APIs? [duplicate]

问题

This question already has an answer here:

• Lower case “k” in Cocoa 2 answers

I've run across many examples of Core Foundation variables named k + someVariableNameHere or k + APILibraryName(2Char) + someVariableNameHere. What does this prefix K indicate?

Examples include:

kGLPFAStereo
kCollectionLockBit
kSetDebugOption

回答1:

The k means constant in hungarian notation... see Lower case "k" in Cocoa.

回答2:

This is a naming convention from the early days of macintosh programming. It indicates a constant.

来源：https://stackoverflow.com/questions/675816/what-does-the-k-prefix-indicate-in-apples-apis