Which of the following range is a valid long double (Turbo C in 16 bit DOS OS)?

fmod(x,y) - Calculates x modulo y, the remainder of x/y.
This function is the same as the modulus operator. But fmod() performs floating point divisions.

Example:

#include <stdio.h>
#include <math.h>

int main ()
{
  printf ("fmod of 5.5 by 1.3 is %lf\n", fmod (5.5, 1.3) );
  return 0;
}

Output:
fmod of 5.5 by 1.3 is 0.300000

Rounding off a value means replacing it by a nearest value that is approximately equal or smaller or greater to the given number.

y = (int)(x + 0.5); here x is any float value. To roundoff, we have to typecast the value of x by using (int)

Example:

#include <stdio.h>

int main ()
{
  float x = 3.6;
  int y = (int)(x + 0.5);
  printf ("Result = %d\n", y );
  return 0;
}

Output:
Result = 4.

Given 3.14 is a double constant.
To specify 3.14 as float, we have to add f to the 3.14. (i.e 3.14f)

Given 3.14 is a double constant.

To specify 3.14 as long double, we have to add L to the 3.14. (i.e 3.14L)

math.h is a header file in the standard library of C programming language designed for basic mathematical operations.

Declaration syntax: double log(double);

The floating point data types are called real data types. Hence float, double, and long double are real data types.