将数组循环到另一个数组，考虑所有可能性

Question

我想做的是..。

我有一个名为char的数组和一个字符串

$char = array("-","_","|","+","~");
$MyString = "this is test string";

我想做的是用数组中的一个字符替换$MyString中的每个空格

但我希望结果是这样

​

​

$MyString = "this is test string";
$ExplodedString = explode(" ",$MyString);

foreach ($char as $sinchar) {
        $text1 = preg_replace("/ /", $sinchar, $MyString ,1);
       foreach ($char as $sinchar) {
        $text2 = preg_replace("/ /", $sinchar, $text1 ,1);
        //echo $text2."\n";
            foreach ($char as $sinchar) {
                $text3 = preg_replace("/ /", $sinchar, $text2 ,1);
                echo $text3."\n";
            }
       }
}

这段代码对我来说很好，但是它是静态代码，我正在寻找更动态的代码，所以如果我添加了一个有更多空格的文本，我就不必再添加一个循环了。

伙计们有什么解决办法吗？

Answer 1

您可以使用递归函数，将第一个单词的排列与其余单词的所有可能的排列组合起来：

function computeAllPermutations(array $words, array $separators): array
{
  switch (count($words)) {
    case 0:
      return [];
    case 1:
      return [$words[0]];
    default:
      $permutations = [];
      foreach (computeAllPermutations(array_slice($words, 1), $separators) as $subPermutation) {
        foreach ($separators as $separator) {
          $permutations[] = $words[0] . $separator . $subPermutation;
        }
      }
      return $permutations;
  }
}

用法：

$words = preg_split('/\h+/', $MyString);
$permutations = computeAllPermutations($words, $char);
print_r($permutations);