設置PHP嵌套變量

Question

我有下面的代碼工作：

$apple_color = "red"; 
$pear_color = "green"; 
$banana_color = "yellow"; 
$grape_color = "purple"; 

foreach(array("apple","pear","banana","grape") as $idx=>$fname) { 
    $var = "${fname}_color"; 
    echo "$var = ${$var}<br>".PHP_EOL; 
} 

但是，我無法弄清楚如何消除是$ var變量像這樣縮短了代碼：

foreach(array("apple","pear","banana","grape") as $idx=>$fname) { 
    echo "${fname}_color = ${${fname}_color}<br>".PHP_EOL; 
} 

的 「$ {$ {FNAME} _Color」 返回，說： 「語法錯誤，意外 '_Color'（T_STRING）」

PHP小提琴的PHP錯誤：http://phpfiddle.org/lite/code/wrfp-yqkx

Answer 1

這個怎麼樣？使用${'string'}建設

foreach(["apple","pear","banana","grape"] as $fname) { 
    echo "{$fname}_color = ".${$fname.'_color'}."<br>".PHP_EOL; 
} 

Answer 2

使用字符串格式化來簡化你的生活：

echo sprintf('$%s_color = %s<br>' . PHP_EOL, $fname, ${$fname . '_color'}); 

Answer 3

而不必爲每種顏色獨立的變量，顏色保存在由水果名稱索引的數組。這樣可以避免使用變量變量的混亂。

$colors = [ 
    'apple' => 'red', 
    'pear' => 'green', 
    'banana' => 'yellow', 
    'grape' => 'purple' 
]; 

foreach (["apple","pear","banana","grape"] as $fname) { 
    echo "{$fname}_color = $colors[$fname]<br>".PHP_EOL; 
}