In C, random numbers can be generated using the rand() function, which is part of the C standard library <stdlib.h>. By default, rand() produces pseudo-random numbers in the range from 0 to RAND_MAX (a constant defined in <stdlib.h>).
rand()
<stdlib.h>.
RAND_MAX
<stdlib.h>
Rounding numbers in C can be accomplished using various functions, but the most common approach involves the floor(), ceil(), and round() functions.
floor()
ceil()
round()
In C, complex numbers are supported by the Standard Library, specifically <complex.h>.
<complex.h>