PHP floor() Function

The floor() function is a built-in PHP function that accepts any float number as argument and rounds it down to the next lowest integer. This function always returns a float number as the range of float is bigger than that of integer.

Syntax

floor ( float $num ) : float

Parameters

Return Value

The floor() function returns the largest integer less than or equal to the given parameter as a float value.

Examples

Basic Usage

Here's a simple example demonstrating the floor() function with a negative number −

<?php
    $arg = -3.95;
    $val = floor($arg);
    echo "floor(" . $arg . ") = " . $val;
?>

floor(-3.95) = -4

Multiple Examples

Let's see how floor() works with different types of numbers −

<?php
    echo "floor(4.7) = " . floor(4.7) . "
";
    echo "floor(4.2) = " . floor(4.2) . "
";
    echo "floor(-2.1) = " . floor(-2.1) . "
";
    echo "floor(-2.9) = " . floor(-2.9) . "
";
    echo "floor(5) = " . floor(5) . "
";
?>

floor(4.7) = 4
floor(4.2) = 4
floor(-2.1) = -3
floor(-2.9) = -3
floor(5) = 5

Key Points

• For positive numbers, floor() removes the decimal part
• For negative numbers, it rounds toward negative infinity
• Always returns a float, even when the input is an integer
• Available in PHP 4.x, 5.x, and 7.x versions

Conclusion

The floor() function is useful for rounding numbers down to the nearest integer. Remember that it always rounds toward negative infinity, which affects how negative numbers are handled.