php實作傳回離當前數字最近的數

本文介绍下，用php实现返回离当前数字最近的数，代码不复杂，适合学习参考。

实现如下的功能： 在一个指定的范围内返回上一个和下一个最接近的数字。

代码如下：

<?php
/**
* 返回离当前数字最近的数
* edit bbs.it-home.org
*/
function NextRelatedNumber($number, $range){   
    $r = $number % $range;
    $f = $number - $r;
    $b = round($r / $range, 0);
  
    return ($b == 1) ? $f + $range : $f;   
}
  
// Returns the next higher number
function NextHigherNumber($number, $range){   
    $r = $number % $range;
    $f = $number - $r;
    $b = ceil($r / $range);
  
    return ($b == 1) ? $f + $range : $f;   
}
  
// Returns the next lower number
function NextLowerNumber($number, $range){   
    $r = $number % $range;
    $f = $number - $r;
    $b = floor($r / $range);
  
    return ($b == 1) ? $f + $range : $f;   
}
  
// Returns the next related number from an array
function NextNumberArray($Number, $NumberRangeArray){
  
    $w = 0;
    $c = -1;
    $abstand = 0;
  
    $l = count($NumberRangeArray);       
    for($pos=0; $pos < $l; $pos++){
  
        $n = $NumberRangeArray[$pos];
  
        $abstand = ($n < $Number) ? $Number - $n : $n - $Number;
  
        if ($c == -1){
            $c = $abstand;
            continue;
        }
        else if ($abstand < $c){
            $c = $abstand;
            $w = $pos;
        }
    }
  return $NumberRangeArray[$w];
}
  
//调用示例
  
// 0 10 20 30 40 50 ...
print 'NextRelatedNumber: ';
print NextRelatedNumber(44, 10) . "\n";
// returns --> 40
  
// 0 20 40 60 80 100 ...
print 'NextHigherNumber: ';
print NextHigherNumber(41, 20) . "\n";
// returns --> 60
  
// 0 5 10 15 20 25 30 35 ...
print 'NextLowerNumber: ';
print NextLowerNumber(57, 5) . "\n";
// returns --> 55
  
//带数组的例子
print 'NextNumberArray: ';
print NextNumberArray(45, array(3, 8, 19, 34, 56, 89)) . "\n";
// returns --> 34
// (45 is between 34 and 56 but 34 is the next)
?>