I took a quiz in my CS class today and got a question about the modulo operator wrong because I didn't know about the availability of % in C, I've been using fmod(). Why do both exist? Is one better/faster or do they just deal with different data types?
modulo division using % operator in C only works for integer operands and returns an integer remainder of the division.
The function fmod accepts double as arguments meaning that it accepts non-integer values and returns the remainder of the division.
Additional note on fmod: how is the remainder calculated in case of double operand? Thanks @chux for showing the documentation on how fmod calculates the remainder of a floating point division.
The floating-point remainder of the division operation x/y calculated by this function is exactly the value x - n*y, where n is x/y with its fractional part truncated.
The returned value has the same sign as x and is less or equal to y in magnitude.
On the other hand, when the modulo division binary operator (%) was first designed, it was determined by the language designers that it would only support operands of 'integer' types because technically speaking, the notion of 'remainder' in mathematics only applies to integer divisions.