How to display hexadecimal numbers in C?

Try:

printf("%04x",a);

• 0 – Left-pads the number with
  zeroes (0) instead of spaces, where
  padding is specified.
• 4 (width) – Minimum number of
  characters to be printed. If the
  value to be printed is shorter than
  this number, the result is right justified
  within this width by padding on the left
  with the pad character. By default this is
  a blank space, but the leading zero we used
  specifies a zero as the pad char.
  The value is not truncated even if the result is
  larger.
• x – Specifier for hexadecimal
  integer.

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