How do printf()'s format specifiers %e and %f differ in their treatment of floating-point numbers?

%e always displays an argument of type double in engineering notation; %f always displays an argument of type double in decimal notation.

%e expects a corresponding argument of type double; %f expects a corresponding argument of type float.

%e displays a double in engineering notation if the number is very small or very large. Otherwise, it behaves like %f and displays the number in decimal notation.

%e displays an argument of type double with trailing zeros; %f never displays trailing zeros.

%e and %f both expect a corresponding argument of type double and format it identically. %e is left over from K&R C; Standard C prefers %f for new code.