# Ceil and Floor functions in C++

In mathematics and computer science, the floor and ceiling functions map a real number to the greatest preceding or the least succeeding integer, respectively.

floor(x) : Returns the largest integer that is smaller than or equal to x (i.e : rounds downs the nearest integer).

```// Here x is the floating point value.
// Returns the largest integer smaller
// than or equal to x
double floor(double x)  ```

Examples of Floor:

```Input : 2.5
Output : 2

Input : -2.1
Output : -3

Input : 2.9
Output : 2
```
 `// C++ program to demonstrate floor function ` `#include ` `#include ` `using` `namespace` `std; ` ` `  `// Driver function ` `int` `main() ` `{ ` `    ``// using floor function which return ` `    ``// floor of input value ` `    ``cout << ``"Floor is : "` `<< ``floor``(2.3) << endl; ` `    ``cout << ``"Floor is : "` `<< ``floor``(-2.3) << endl; ` ` `  `    ``return` `0; ` `} `

Output:

```Floor is : 2
Floor is : -3
```

ceil(x) : Returns the smallest integer that is greater than or equal to x (i.e : rounds up the nearest integer).

```// Here x is the floating point value.
// Returns the smallest integer greater
// than or equal to x
double ceiling(double x)  ```

Examples of Ceil:

```Input : 2.5
Output : 3

Input : -2.1
Output : -2

Input : 2.9
Output : 3
```
 `// C++ program to demonstrate ceil function ` `#include ` `#include ` `using` `namespace` `std; ` ` `  `// Driver function ` `int` `main() ` `{ ` `    ``// using ceil function which return ` `    ``// floor of input value ` `    ``cout << ``" Ceil is : "` `<< ``ceil``(2.3) << endl; ` `    ``cout << ``" Ceil is : "` `<< ``ceil``(-2.3) << endl; ` ` `  `    ``return` `0; ` `} `

```Ceil is : 3
Ceil is : -2
```

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