如何使用php搜索字符串中的smiler单词

$string = "This is a sample string with smiler word.";
$word = "smiler";

if (strpos($string, $word) !== false) {
    echo "单词 '$word' 存在于字符串中。";
} else {
    echo "单词 '$word' 不存在于字符串中。";
}

$string = "This is a sample string with Smiler word.";
$word = "smiler";

if (stripos($string, $word) !== false) {
    echo "单词 '$word' 存在于字符串中。";
} else {
    echo "单词 '$word' 不存在于字符串中。";
}