*
     * @param val the integer value to convert to hexadecimal characters
     * @param dst the destination character array to write the hex digits into
     * @param dstIndex the starting index in the destination array
     * @param size the number of hex digits to write (will be left-padded with zeros)
     */
    public static void toHexChars(int val, final char dst[], final int dstIndex, int size) {

    }

    @Test
    void isAllDigitsHandlesEmptyString() {
        // Empty string technically has no non-digit characters, so it returns true
        assertTrue(UniAddress.isAllDigits(""), "isAllDigits should return true for empty string (no non-digits)");
    }

    /* ---------------------------------------------------------------------

     *
     * @param val the integer value to convert to hexadecimal characters
     * @param dst the destination character array to write the hex digits into
     * @param dstIndex the starting index in the destination array
     * @param size the number of hex digits to write (will be left-padded with zeros)
     */
    public static void toHexChars(int val, final char dst[], final int dstIndex, int size) {

	"strings"
	"time"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
	"gorm.io/gorm/logger"
	"gorm.io/gorm/schema"
)

// This regular expression seeks to find a sequence of digits (\d+) among zero or more non-digit characters (\D*),
// with a possible trailing non-digit character (\D?).

// For example, values that can pass this regular expression are:
// - "123"
// - "abc456"
// -"%$#@789"

		// like an IP address.
		isNotNumber := false
		for i := range len(piece) {
			switch {
			case (piece[i] >= 'a' && piece[i] <= 'z' ||
				piece[i] == '-'):
				// Found a non-digit character, so
				// this piece is not a number.
				isNotNumber = true
			case piece[i] >= '0' && piece[i] <= '9':
				// Nothing to do.
			default:
				// Found invalid character.
				return false
			}

    /**
     * Convert hexadecimal characters to binary integer
     *
     * @param arr the character array containing hex digits
     * @param offset the starting position in the array
     * @param length the number of hex digits to convert
     * @return the integer value of the hex digits
     */
    public static int hex_to_bin(final char[] arr, final int offset, final int length) {
        int value = 0;

    }

    /**
     * Checks if the given character is a valid URL character.
     *
     * Valid URL characters include:
     * - Lowercase letters (a-z)
     * - Uppercase letters (A-Z)
     * - Digits (0-9)
     * - Special characters: . - * _ : / + % = & ? # [ ] @ ~ ! $ ' ( ) , ;
     *
     * @param c the character to check
     * @return {@code true} if the character is a valid URL character, {@code false} otherwise

 * <ul>
 * <li>Mixing of '<code>-</code>' (hyphen) and '<code>.</code>' (dot) separators,</li>
 * <li>Transition between characters and digits also constitutes a separator:
 *     <code>1.0alpha1 =&gt; [1, [alpha, 1]]</code></li>
 * <li>Unlimited number of version components,</li>
 * <li>Version components in the text can be digits or strings,</li>
 * <li>Strings are checked for well-known qualifiers, and the qualifier ordering is used for version ordering.

        if ((s.length() > 1) && s.startsWith("0")) {
            return null;
        }
        return tryParseInt(s);
    }

    private static Integer tryParseInt(String s) {
        // for performance, check digits instead of relying later on catching NumberFormatException
        if (!isDigits(s)) {
            return null;
        }

        try {
            long longValue = Long.parseLong(s);

///

## About HTTP status codes { #about-http-status-codes }

/// note

If you already know what HTTP status codes are, skip to the next section.

///

In HTTP, you send a numeric status code of 3 digits as part of the response.

These status codes have a name associated to recognize them, but the important part is the number.

In short: