php 匹配

<?php
$text = "Hello, world!";
$needle = "world";

if (strpos($text, $needle) !== false) {
    echo "Found '$needle' in the text.";
} else {
    echo "'$needle' was not found.";
}
?>

<?php
$text = "The quick brown fox jumps over the lazy dog.";
$pattern = "/\b\w{5}\b/"; // 匹配五个字母的单词

if (preg_match($pattern, $text, $matches)) {
    echo "Found a match: " . $matches[0];
} else {
    echo "No match found.";
}
?>

<?php
$text = "Hello, world!";
$pattern = "/\b\w{5}\b/"; // 正确的正则表达式

if (preg_match($pattern, $text, $matches) === false) {
    echo "Error: " . preg_last_error();
} else {
    echo "Found a match: " . $matches[0];
}
?>

<?php
$text = "Hello, World!";
$pattern = "/world/i"; // 不区分大小写

if (preg_match($pattern, $text, $matches)) {
    echo "Found a match: " . $matches[0];
} else {
    echo "No match found.";
}
?>