explode() 在空格上，然后使用 [] 符号来访问作为数组的结果字符串:

explode() on the spaces, then you use the [] notation to access the resultant strings as arrays:

$words = explode(" ", "Community College District");
$acronym = "";

foreach ($words as $w) {
  $acronym .= $w[0];
}

如果您期望多个空格可以分隔单词，请改用 preg_split()

If you have an expectation that multiple spaces may separate words, switch instead to preg_split()

$words = preg_split("/\s+/", "Community College District");

或者，如果不是空格的字符分隔单词 (-,_)，例如，也使用 preg_split():

Or if characters other than whitespace delimit words (-,_) for example, use preg_split() as well:

// Delimit by multiple spaces, hyphen, underscore, comma
$words = preg_split("/[\s,_-]+/", "Community College District");