if语句-比较运算符“；如果“；在PHP中 - if statement - Comparison Operator "IF" in PHP

if statement - Comparison Operator "IF" in PHP

可能重复：
嵌套php三元故障：三元输出！=if-else

为什么这样做：

if($db->f('item_bonus') > 0)
    $bonus = $db->f('item_bonus').' (i)';
elseif($db->f('manufacturer_bonus') > 0)
    $bonus = $db->f('manufacturer_bonus').' (m)';
elseif($db->f('category_bonus') > 0)
    $bonus = $db->f('category_bonus'). ' (c)';

但这不起作用：

$bonus = $db->f('item_bonus') > 0 ? $db->f('item_bonus').' (i)' : $db->f('manufacturer_bonus') > 0 ? $db->f('manufacturer_bonus').' (m)' : $db->f('category_bonus') > 0 ? $db->f('category_bonus'). ' (c)' : '0';

我做错了什么？$db->f返回编号，浮点类型。

尝试分组：

$bonus = $db->f('item_bonus') > 0 ? $db->f('item_bonus').' (i)' : ($db->f('manufacturer_bonus') > 0 ? $db->f('manufacturer_bonus').' (m)' : ($db->f('category_bonus') > 0 ? $db->f('category_bonus'). ' (c)' : '0'));

它最好将三元运算符与简单的if/else语句一起使用，这样在将来需要再次检查代码时就可以理解它们。所以在这种情况下，最好让你发布的第一段代码。

如果您的推理是取消硬编码If语句，则可以将函数和数据分离。。。

// Important stuff
// Change the order of bonus importance using this array
$bonus_precedence = array("item", "manufacturer", "category");
// Change the symbol for each item with this associative array
$bonus_markers = array(
  "item" => "i",
  "manufacturer" => "m",
  "category" => "c"
);
// Magic beyond here
foreach($bonus_precedence as $bonus_type) {
  // Get the next bonus type
  $bonus = $db->f("{$bonus_type}_bonus");
  // Was there a bonus
  if($bonus > 0) {
    // Output the bonus in full and break the loop
    $bonus_marker = $bonus_markers[$bonus_type];
    $bonus .= " ($bonus_marker)";
    break;
  } 
}

如果它是硬编码的并不重要，那么就坚持使用long-If语句。你可以很容易地评论它，它很容易阅读和评论：

// Only one bonus type is allowed
// Item bonuses are the most important if there is
// an item bonus we ignore all other bonuses
if($db->f("item_bonus") > 0) {
  $bonus = "{$db->f("item_bonus")} (i)";
// Manufacturer bonuses are the next most important
} elseif($db->f("manufacturer_bonus") > 0) {
  $bonus = "{$db->f("manufacturer_bonus")} (m)";
// Category bonus is the fallback if there are no 
// other bonuses
} elseif($db->f("category_bonus") > 0) {
  $bonus = "{$db->f("category_bonus")} (c)";
}

否则，至少试着让它变得容易理解：

// Only one bonus type is allowed
$bonus = 
  // Item bonuses are the most important if there is
  // an item bonus we ignore all other bonuses
  ($db->f("item_bonus") > 0 ? "{$db->f("item_bonus")} (i)" : 
    // Manufacturer bonuses are the next most important
    ($db->f("manufacturer_bonus") > 0 ? "{$db->f("manufacturer_bonus")} (m)" : 
      // Category bonus is the fallback if there are no 
      // other bonuses
      ($db->f("category_bonus") > 0 ? "{$db->f("category_bonus")} (c)" : "0")
    )
  );