Question

如何使用PHP将整数向下舍入到最接近的3的倍数？并且＆lt; 3为0。

例如： 4变为3
10变为9
9变为9
8变为6

等等......

Answer 1

假设$x是您的输入：

print $x-$x%3;

Answer 2

这就是你要找的。

/**
 * Round an integer down to the nearest multiple of the given multiple
 * @param integer $number
 * @param integer $multiple
 * @return integer
 */
 function round_down_to_multiple_of( int $number, int $multiple = 3 ): int
 {
    return (int)($multiple * floor( $number/$multiple ));
 }

 # TESTS
 $numbers = [ 10, 9, 8, 1, 0 ];
foreach( $numbers as $number ){
    printf( '%d became %d'.PHP_EOL, $number, round_down_to_multiple_of( $number, 3 ) );
}

运行上述测试后，我得到以下结果：

10 became 9
9 became 9
8 became 6
1 became 0
0 became 0

Answer 3

我误读了即使它是完美契合，它应该向下舍入到 last 之前的增量：

4变为3
  10变为9
  9变为6
  8变为6

因此，如果由于某种原因你需要这个;你的答案是：

print $x-($x-1)%3-1;

我在理解这个问题时犯了一个错误，但认为这个答案非常好奇，值得发帖。

如何在PHP中向下舍入到最接近的3的倍数？

3 个答案: