# 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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