nextafter() and nexttoward() in C/C++

How would you solve below problems in C/C++?

What is the smallest representable positive floating point number in C/C++?
What is the largest representable negative floating point number in C/C++?
Given a positive floating point number x, find the largest representable floating point value smaller than x?

nextafter(x, y) and nexttoward(x.y)
In C and C++, both nextafter(x, y) and nexttoward(x.y) are similar functions defined in math.h or cmath header files. They both return next representable value after x in the direction of y. nexttoward() has more precise second parameter y.

The following program demonstrates the concept :

// C program to demonstrate use of nextafter() and nexttoward() 
#include <stdio.h> 
#include <math.h> 
int main () 
{ 
    // using nextafter 
    printf ("Smallest positive floating point number : %e\n", 
            nextafter(0.0, 1.0)); 
    printf ("Largest negative floating point number :%e\n", 
            nextafter(0.0, -1.0)); 
    printf ("Largest positive floating point number smaller than 0.5 : %e\n", 
            nextafter(0.5, 0.0)); 
  
    // using nexttoward 
    printf ("Smallest positive floating point number : %e\n", 
            nexttoward(0.0, 1.0)); 
    printf ("Largest negative floating point number : %e\n", 
            nexttoward(0.0, -1.0)); 
    printf ("Largest positive floating point number smaller than 0.5 : %e\n", 
            nexttoward(0.5, 0.0)); 
    return (0); 
} 

Output:

nextafter first value greater than zero: 4.940656e-324
nextafter first value less than zero: -4.940656e-324
nexttoward first value greater than zero: 4.940656e-324
nexttoward first valnextafter first value greater than zero: 4.940656e-324
nextafter first value less than zero: -4.940656e-324
nexttoward first value greater than zero: 4.940656e-324
nexttoward first value less than zero: -4.940656e-324 ue less than zero: -4.940656e-324

This article is contributed by Aditya Chatterjee. If you like GeeksforGeeks and would like to contribute, you can also write an article and mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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