在字符串中搜索与PHP关联数组中的键匹配的子字符串的最简单方法是什么？

Question

I'm fairly new to PHP and I need a function that will check if a string input from the user contains a substring matching a key in an associative array.

So far I've been using the array_key_exists() function a lot to check if the input ~matches~ a key in an array, but I don't know how to go about doing this unless I search for each key one at a time. Maybe some kind of loop would be useful?

My code looks something like this:

<form method="post" autocomplete="off">
   <textarea id="wiyetxt" name="input"></textarea>
   <input type="submit" value="Send">
   <input type="reset" value="Clear">
</form>

$input = $_POST["input"];
$keywords = ["apple" => "Found 'apple'", "banana" => "Found 'banana'", 
  "carrot" => "Found 'carrot'"];
if ($input contains one of these keys) {
  echo(value which corresponds to the key);
}
else {
  echo("No keys were found");
}

Answer 1

A foreach loop to search all the keywords, if the key value exists within $input, print the key's value.

 $keywords = ["apple" => "Found 'apple'", "banana" => "Found 'banana'",  "carrot" => "Found 'carrot'"];
  foreach ($keywords as $k => $v)
  {
     if (strstr($input, $k))
        print $v;

  }