floor
(PHP 4, PHP 5, PHP 7, PHP 8)
floor — 舍去法取整
参数
num-
要取整的数字
返回值
对 num 向下取整。floor() 返回的类型仍然是
float。
更新日志
| 版本 | 说明 |
|---|---|
| 8.0.0 |
num 不再接受支持数字转换的内部对象。
|
示例
示例 #1 floor() 示例
<?php
echo floor(4.3); // 4
echo floor(9.999); // 9
echo floor(-3.14); // -4
?>
＋添加备注
用户贡献的备注 3 notes
Antonio ¶
5 years ago
<?php
echo (2.3 * 100) . ' - ' . round(2.3 * 100, 0) . ' - ' . floor(2.3 * 100);
?>.
Result:
230 - 230 - 229
Be careful!
jay at w3prodigy dot com ¶
16 years ago
Note:
<?php
$int = 0.99999999999999999;
echo floor($int); // returns 1
?>
and
<?php
$int = 0.9999999999999999;
echo floor($int); // returns 0
?>
jolyon at mways dot co dot uk ¶
20 years ago
Beware of FLOAT weirdness!
Floats have a mind of their own, and what may look like an integer stored in a float isn't.
Here's a baffling example of how floor can be tripped up by this:
<?php
$price = 79.99;
print $price."\r\n"; // correct result, 79.99 shown
$price = $price * 100;
print $price."\r\n"; // correct result, 7999 shown
print floor($price); // 7998 shown! what's going on?
?>
The thing to remember here is that the way a float stores a value makes it very easy for these kind of things to happen. When the 79.99 was multiplied by 100, the actual value stored in the float was probably something like 7998.9999999999999999999999999999999999, PHP would print out 7999 when the value is displayed but floor would therefore round this down to 7998.
THe moral of this story - never use float for anything that needs to be accurate! If you're doing prices for products or a shopping cart, then always use an integer and store prices as a number of pence, you'll thank me for this later :)