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

CPP

// C++ program to demonstrate floor function
#include <iostream>
#include <cmath>
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

CPP

// C++ program to demonstrate ceil function
#include <iostream>
#include <cmath>
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

Let us see the differences in a tabular form -:

	ceil	floor
1.	It is used to return the smallest integral value n that is not less than n.	It is used to return the largest integral value n that is not greater than n.
2.	It rounds the n upwards.	It rounds the n downwards.
3.	Its syntax is -: data_type ceil (n);	Its syntax is -: data_type floor (n);
4.	It takes only one parameter that is the value to round up.	It takes only one parameter that is the value to round up.

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