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C++ floor()

In this tutorial, we will learn about the C++ floor() function with the help of examples.

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

It is defined in the cmath header file.

Example

#include <iostream>
#include <cmath>
using namespace std;

int main() {

// get the largest possible integer less than or equal to 68.95 cout << floor(68.95);
return 0; } // Output: 68

floor() Syntax

The syntax of the floor() function is:

floor(double num);

floor() Parameters

The floor() function takes the following parameters:

  • num - a floating point number whose floor value is computed. It can be of the following types:
    • double
    • float
    • long double

floor() Return Value

The floor() function returns:

  • the largest possible integer value which is less than or equal to num

floor() Prototypes

The prototypes of the floor() function as defined in the cmath header file are:

double floor(double num);

float floor(float num);

long double floor(long double num);

// for integral types
double floor(T num);

Example 1: C++ floor()

#include <iostream>
#include <cmath>
using namespace std;

int main() {
  double num, result;

num = 10.25; result = floor(num);
cout << "Floor of " << num << " = " << result << endl;
num = -34.251; result = floor(num);
cout << "Floor of " << num << " = " << result << endl;
num = 0.71; result = floor(num);
cout << "Floor of " << num << " = " << result; return 0; }

Output

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

Example 2: C++ floor() for Integral Types

#include <iostream>
#include <cmath>
using namespace std;

int main() {
  double result;

int num = 15; result = floor(num);
cout << "Floor of " << num << " = " << result; return 0; }

Output

Floor of 15 = 15

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

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