Ceil and Floor functions in C++ (original) (raw)

Last Updated : 16 May, 2025

**C++ provides floor() and ceil() functions, defined in the <****cmath**> header file, to find the **rounded-down and **rounded-up values of floating-point numbers

floor() Function

**floor() function takes floating point number as input and returns the largest integer that is smaller than or equal to the value passed as the argument.

**Syntax:

C++ `

floor(num);

`

**Example:

CPP `

#include #include using namespace std;

int main() {

// using floor function which 
// return floor of input value
cout << "Floor of 2.3 is : " 
     << floor(2.3) << endl;
cout << "Floor of -2.3 is : " 
     << floor(-2.3);
return 0;

}

`

Output

Floor of 2.3 is : 2 Floor of -2.3 is : -3

ceil() Function

**ceil() function in C++ returns the smallest integer that is greater than or equal to the value passed as the input argument.

**Syntax:

C++ `

ceil(num);

`

**Example:

C++ `

#include #include using namespace std;

int main() {

// using ceil function which return
// floor of input value
cout << " Ceil of 2.3 is : " 
     << ceil(2.3) << endl;
cout << " Ceil of -2.3 is : " 
     << ceil(-2.3);
return 0;

}

`

Output

Ceil of 2.3 is : 3 Ceil of -2.3 is : -2

Difference between ceil() and floor() in C++

The ceil and floor functions are important for rounding numbers. Let us see the differences between ceil() and floor() functions in tabular form: