# Ceil and Floor functions in C++

• Difficulty Level : Easy
• Last Updated : 04 Apr, 2018

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
```

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