C++ ceil()

The ceil() function in C++ returns the smallest possible integer value which is greater than or equal to the given argument.

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

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

The ceil() function in C++ returns the smallest possible integer value which is greater than or equal to the given argument. This function is defined in <cmath> header file.

ceil() Parameters

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

ceil() Return value

The ceil() function returns the smallest possible integer value which is greater than or equal to the given argument.

Example 1: ceil() function for double, float and long double types

#include <iostream>
#include <cmath>

using namespace std;

int main()
{
    double x = 10.25, result;
    result = ceil(x);
    cout << "Ceil of " << x << " = " << result << endl;
    return 0;
}

When you run the program, the output will be:

Ceil of 10.25 = 11

Example 2: ceil() function for integral types

#include <iostream>
#include <cmath>

using namespace std;

int main()
{
    int x = 15;
    double result;
    result = ceil(x);
    cout << "Ceil of " << x<< " = " << result << endl;
    return 0;
}

When you run the program, the output will be:

Ceil of 15 = 15

For integral types, you will always get the same result, so this function is not used with integral types in practice.