floor, floorf, floorl - largest integral value not greater than argument

```
#include <math.h>
double floor(double x);
float floorf(float x);
long double floorl(long double x);
```

Link with `-lm`

.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

These functions return the largest integral value that is not greater
than `x`

.

For example, `floor(0.5)`

is 0.0, and `floor(-0.5)`

is
-1.0.

These functions return the floor of `x`

.

If `x`

is integral, +0, -0, NaN, or an infinity, `x`

itself is returned.

No errors occur. POSIX.1-2001 documents a range error for overflows, but see NOTES.

For an explanation of the terms used in this section, see attributes(7).

Interface | Attribute | Value |

floor(), floorf(), floorl() | Thread safety | MT-Safe |

C99, POSIX.1-2001, POSIX.1-2008.

The variant returning `double`

also conforms to SVr4, 4.3BSD,
C89.

SUSv2 and POSIX.1-2001 contain text about overflow (which might set
`errno`

to **ERANGE**, or raise an
**FE_OVERFLOW** exception). In practice, the result cannot
overflow on any current machine, so this error-handling stuff is just
nonsense. (More precisely, overflow can happen only when the maximum
value of the exponent is smaller than the number of mantissa bits. For
the IEEE-754 standard 32-bit and 64-bit floating-point numbers the
maximum value of the exponent is 128 (respectively, 1024), and the
number of mantissa bits is 24 (respectively, 53).)

This page is part of release 5.10 of the Linux `man-pages`

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and the latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.