How can PHP developers handle cases where the input string format may vary, such as the presence or absence of "EX:" before a date in the input?

When dealing with varying input string formats, PHP developers can use regular expressions to match different patterns and extract the necessary information. In this case, developers can create a regular expression pattern that accounts for both cases where "EX:" is present or absent before a date in the input string. By using preg_match or similar functions, developers can extract the date information regardless of the format.

$input = "EX: 2022-12-31";
$pattern = "/(?:EX: )?(\d{4}-\d{2}-\d{2})/";
if (preg_match($pattern, $input, $matches)) {
    $date = $matches[1];
    echo $date; // Output: 2022-12-31
} else {
    echo "Date not found in input string.";
}