/C

# floor, floorf, floorl

float       floorf( float arg );
(1) (since C99)
double      floor( double arg );
(2)
long double floorl( long double arg );
(3) (since C99)
#define floor( arg )
(4) (since C99)
1-3) Computes the largest integer value not greater than arg.
4) Type-generic macro: If arg has type long double, floorl is called. Otherwise, if arg has integer type or the type double, floor is called. Otherwise, floorf is called.

### Parameters

 arg - floating point value

### Return value

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

Return value
Argument

### 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

### 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 intmax_t), when stored in an integer variable.

### Example

#include <math.h>
#include <stdio.h>
int main(void)
{
printf("floor(+2.7) = %+.1f\n", floor(2.7));
printf("floor(-2.7) = %+.1f\n", floor(-2.7));
printf("floor(-0.0) = %+.1f\n", floor(-0.0));
printf("floor(-Inf) = %+f\n",   floor(-INFINITY));
}

Possible output:

floor(+2.7) = +2.0
floor(-2.7) = -3.0
floor(-0.0) = -0.0
floor(-Inf) = -inf

### References

• C11 standard (ISO/IEC 9899:2011):
• 7.12.9.2 The floor functions (p: 251)
• 7.25 Type-generic math <tgmath.h> (p: 373-375)
• F.10.6.2 The floor functions (p: 526)
• C99 standard (ISO/IEC 9899:1999):
• 7.12.9.2 The floor functions (p: 232)
• 7.22 Type-generic math <tgmath.h> (p: 335-337)
• F.9.6.2 The floor functions (p: 463)
• C89/C90 standard (ISO/IEC 9899:1990):
• 4.5.6.3 The floor function