How can PHP be used to search for specific patterns in a string, such as placeholders?

To search for specific patterns in a string, such as placeholders, in PHP, you can use regular expressions. Regular expressions allow you to define a pattern to search for within a string and then use functions like preg_match() to find matches. By using regular expressions, you can easily search for placeholders or other specific patterns in a string and extract the information you need.

$string = "Hello, my name is {name} and I am {age} years old.";
$pattern = '/\{([^}]+)\}/';
preg_match_all($pattern, $string, $matches);

foreach ($matches[1] as $match) {
    echo "Found placeholder: " . $match . "\n";
}