function concat(array $array) {
$current = array_shift($array);
if(count($array) > 0) {
$results = array();
$temp = concat($array);
foreach($current as $word) {
foreach($temp as $value) {
$results[] = $word . ' ' . $value;
}
}
return $results;
}
else {
return $current;
}
}
$a = array(array('dog', 'cat'), array('food', 'tooth'), array('car', 'bike'));
print_r(concat($a));
哪个返回：
Array
(
[0] => dog food car
[1] => dog food bike
[2] => dog tooth car
[3] => dog tooth bike
[4] => cat food car
[5] => cat food bike
[6] => cat tooth car
[7] => cat tooth bike
)
但是我想这对于大型数组会表现不佳，因为输出数组会很大。
function concat(array $array, $concat = '') {
$current = array_shift($array);
$current_strings = array();
foreach($current as $word) {
$current_strings[] = $concat . ' ' . $word;
}
if(count($array) > 0) {
foreach($current_strings as $string) {
concat($array, $string);
}
}
else {
foreach($current_strings as $string) {
echo $string . PHP_EOL;
}
}
}
concat(array(array('dog', 'cat'), array('food', 'tooth'), array('car', 'bike')));
这使：
dog food car
dog food bike
dog tooth car
dog tooth bike
cat food car
cat food bike
cat tooth car
cat tooth bike
通过这种方法，也很容易获得“子隐患”。只需在echo $string . PHP_EOL;之前插入concat($array, $string);，输出为：
dog
dog food
dog food car
dog food bike
dog tooth
dog tooth car
dog tooth bike
cat
cat food
cat food car
cat food bike
cat tooth
cat tooth car
cat tooth bike
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