PHP：array_rand陣列

Question

我有此數組：

$nonTerminals = array("S","A","B"); 
$grammar = array(
"$nonTerminals[0]" => "aA", 
"$nonTerminals[1]" => array("aA","bB"), 
"$nonTerminals[2]" => array("bB","b") 
); 

，我用這個隨機值：

$rand_keys = array_rand($grammar, 2); 
echo $grammar[$rand_keys[0]] . "\n"; 

但這是錯誤的，因爲它給我一些錯誤。

Answer 1

你可以這樣說：

$nonTerminals = array("S","A","B"); 
$grammar = array(
"$nonTerminals[0]" => "aA", 
"$nonTerminals[1]" => array("aA","bB"), 
"$nonTerminals[2]" => array("bB","b") 
); 

$rand_keys = array_rand($grammar, 2); 
if (!is_array($grammar[$rand_keys[0]]) { 
    //This checks if the value is an array or not. 
    echo $grammar[$rand_keys[0]]; 
} 
else { 
    //it is an array, so echo a random value from that array; 
    echo $grammar[$rand_keys[0]][rand(0, 1)]; 
}