如何在php数组中添加条件？

Question

这是阵列

$anArray = array(
   "theFirstItem" => "a first item",
   if(True){
     "conditionalItem" => "it may appear base on the condition",
   }
   "theLastItem"  => "the last item"

);

但是我得到PHP Parse错误,为什么我可以在数组中添加一个条件,会发生什么？:

PHP Parse error:  syntax error, unexpected T_IF, expecting ')'

Answer 1

不幸的是,根本不可能.

如果拥有该项但具有NULL值,则使用此:

$anArray = array(
   "theFirstItem" => "a first item",
   "conditionalItem" => $condition ? "it may appear base on the condition" : NULL,
   "theLastItem"  => "the last item"
);

否则你必须这样做:

$anArray = array(
   "theFirstItem" => "a first item",
   "theLastItem"  => "the last item"
);

if($condition) {
   $anArray['conditionalItem'] = "it may appear base on the condition";
}

如果订单很重要,那就更加丑陋了:

$anArray = array("theFirstItem" => "a first item");
if($condition) {
   $anArray['conditionalItem'] = "it may appear base on the condition";
}
$anArray['theLastItem'] = "the last item";

你可以让它更具可读性:

$anArray = array();
$anArray['theFirstItem'] = "a first item";
if($condition) {
   $anArray['conditionalItem'] = "it may appear base on the condition";
}
$anArray['theLastItem'] = "the last item";

Answer 2

如果要创建纯关联数组，并且键的顺序无关紧要，则始终可以使用三元运算符语法有条件地命名键。

$anArray = array(
    "theFirstItem" => "a first item",
    (true ? "conditionalItem" : "") => (true ? "it may appear base on the condition" : ""),
    "theLastItem" => "the last item"
);

这样，如果满足条件，则密钥与数据一起存在。如果不是，那只是一个带有空字符串值的空白键。但是，鉴于已经有很多其他答案，可能有更好的选择来满足您的需求。这不是完全干净，但是如果您正在处理具有大型数组的项目，则可能要比打破数组然后再添加要容易。特别是如果数组是多维的。