What is the difference between the `A` and `W` functions in the Win32 API?

Question

What is the difference in calling the Win32 API function that have an A character appended to the end as opposed to the W character.

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Answer 1

The A functions use Ansi (not ASCII) strings as input and output, and the W functions use Unicode string instead (UCS-2 on NT4 and earlier, UTF-16 on W2K and later). Refer to MSDN for more details.