連續數字之間用連字符縮短數字列表

Question

是否有一個簡單的方法來獲取可能在1-15範圍內的數字列表。並且用短劃線代替連續數字。

這樣，例如，如果你有以下數字：

1 2 3 5 6 7 10 12

它將輸出

1 - 3, 5 - 7, 10, 12

Answer 1

<?php 
$n = array (1, 2, 3, 5, 6, 7, 10, 12); 
sort ($n); // If necessary. 
$i = 0; 
while ($i < count ($n)) 
    { 
    if ($i != 0) 
     print (", "); 
    $rangestart = $i; 
    print ($n [$i++]); 
    while ($i < count ($n) && $n [$i] == $n [$i - 1] + 1) 
     $i++; 
    if ($i > $rangestart + 1) 
     print (" - " . $n [$i - 1]); 
    } 

Answer 2

$n = array (1, 2, 4, 5, 7, 8, 10, 11, 12, 13, 14, 16, 17); 
$lastindex = count($n)-1; 
foreach($n as $k => $i) 
{ 
    if($k == 0) echo $i; 
    elseif($i != $n[$k-1]+1) echo ', ' . $i; 
    elseif($k == $lastindex || $i+1 != $n[$k+1]) echo ' - ' . $i; 
} 

與爆炸功能：

http://codepad.org/DKztLGhe

function shorten($numbers){ 
    $a = explode(' ',$numbers); 
    $lastindex = count($a)-1; 
    $s = ''; 
    foreach($a as $i => $n){ 
    if($i == 0)         $s .=  $n; 
    else if($a[$i-1]+1 != $n)      $s .= ', '.$n; 
    else if($i == $lastindex || $n+1 != $a[$i+1]) $s .= ' - '.$n; 
    } 
    return $s; 
} 

print_r(shorten('').'<br>'); 
print_r(shorten('1').'<br>'); 
print_r(shorten('1 2').'<br>'); 
print_r(shorten('1 3').'<br>'); 
print_r(shorten('1 3 4 6').'<br>'); 
print_r(shorten('1 3 4 6 7').'<br>'); 
print_r(shorten('1 2 3 4 5').'<br>'); 
print_r(shorten('1 2 3 5 6 10 12 13').'<br>');