C++ floor()

The floor() function in C++ returns the largest possible integer value which is less than or equal to the given argument.

floor() prototype [As of C++ 11 standard]

double floor(double x);
float floor(float x);
long double floor(long double x);
double floor(T x); // For integral type

The floor() function takes a single argument and returns a value of type double, float or long double type. This function is defined in <cmath> header file.

floor() Parameters

The floor() function takes a single argument whose floor value is computed.

floor() Return value

The floor() function returns the largest possible integer value which is less than or equal to the given argument.

Example 1: How floor() works in C++?

#include <iostream>
#include <cmath>

using namespace std;

int main()
{
    double x = 10.25, result;
    result = floor(x);
    cout << "Floor of " << x << " = " << result << endl;

    x = -34.251;
    result = floor(x);
    cout << "Floor of " << x << " = " << result << endl;
    
    x = 0.71;
    result = floor(x);
    cout << "Floor of " << x << " = " << result << endl;
    
    return 0;
}

When you run the program, the output will be:

Floor of 10.25 = 10
Floor of -34.251 = -35
Floor of 0.71 = 0

Example 2: floor() function for integral types

#include <iostream>
#include <cmath>

using namespace std;

int main()
{
    int x = 15;
    double result;
    result = floor(x);
    cout << "Floor of " << x << " = " << result << endl;

    return 0;
}

When you run the program, the output will be:

Floor of 15 = 15

The floor of an integral value is the integral value itself, so floor function isn't used on integral values in practice.