Namespaces
Variants
Views
Actions

std::floor

From cppreference.com
< cpp‎ | numeric‎ | math
Revision as of 09:03, 30 June 2014 by Cubbi (Talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
 
 
 
Common mathematical functions
Functions
Basic operations
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)(C++11)(C++11)
Exponential functions
(C++11)
(C++11)
(C++11)
(C++11)
Power functions
(C++11)
(C++11)
Trigonometric and hyperbolic functions
(C++11)
(C++11)
(C++11)
Error and gamma functions
(C++11)
(C++11)
(C++11)
(C++11)
Nearest integer floating point operations
floor
(C++11)(C++11)(C++11)
(C++11)
(C++11)
(C++11)(C++11)(C++11)
Floating point manipulation functions
(C++11)(C++11)
(C++11)
(C++11)
(C++11)(C++11)
(C++11)
Classification/Comparison
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Macro constants
(C++11)(C++11)(C++11)(C++11)(C++11)
 
Defined in header <cmath>
float       floor( float arg );
(1)
double      floor( double arg );
(2)
long double floor( long double arg );
(3)
double      floor( Integral arg );
(4) (since C++11)
1-3) Computes the largest integer value not greater than arg.
4) A set of overloads or a function template accepting an argument of any integral type. Equivalent to 2) (the argument is cast to double).

Contents

[edit] Parameters

arg - floating point value

[edit] Return value

If no errors occur, the largest integer value not greater than arg, that is ⌊arg⌋, is returned.

Return value
math-floor.svg
Argument

[edit] Error handling

Errors are reported as specified in math_errhandling

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

  • The current rounding mode has no effect.
  • If arg is ±∞, it is returned, unmodified
  • If arg is ±0, it is returned, unmodified
  • If arg is NaN, NaN is returned

[edit] Notes

FE_INEXACT may be (but isn't required to be) raised when rounding a non-integer finite value.

The largest representable floating-point values are exact integers in all standard floating-point formats, so this function never overflows on its own; however the result may overflow any integer type (including std::intmax_t), when stored in an integer variable.

[edit] Example

#include <cmath>
#include <iostream>
int main()
{
    std::cout << std::fixed
              << "floor(+2.7) = " << std::floor(+2.7) << '\n'
              << "floor(-2.7) = " << std::floor(-2.7) << '\n'
              << "floor(-0.0) = " << std::floor(-0.0) << '\n'
              << "floor(-Inf) = " << std::floor(-INFINITY) << '\n';
}

Output:

floor(+2.7) = 2.000000
floor(-2.7) = -3.000000
floor(-0.0) = -0.000000
floor(-Inf) = -inf

[edit] See also

nearest integer not less than the given value
(function) [edit]
(C++11)
nearest integer not greater in magnitude than the given value
(function) [edit]
(C++11)(C++11)(C++11)
nearest integer, rounding away from zero in halfway cases
(function) [edit]
C documentation for floor