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# floor, floorf, floorl

From cppreference.com
< c‎ | numeric‎ | math

Defined in header `<math.h>` |  |
float floorf( float arg ); | (1) | (since C99)
double floor( double arg ); | (2) |
long double floorl( long double arg ); | (3) | (since C99)
Defined in header `<tgmath.h>` |  |
#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.

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

### [edit] Example

Run this code

    #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

### [edit] 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

### [edit] See also

ceil ceilf ceill (C99)(C99) | computes smallest integer not less than the given value (function) [edit]
trunc truncf truncl (C99)(C99)(C99) | rounds to nearest integer not greater in magnitude than the given value (function) [edit]
round lround llround (C99)(C99)(C99) | rounds to nearest integer, rounding away from zero in halfway cases (function) [edit]
C++ documentation for floor

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