预定义常量

INTL_MAX_LOCALE_LEN (integer)
Limit on locale length, set to 80 in PHP code. Locale names longer than this limit will not be accepted.
IDNA_DEFAULT (integer)
Prohibit processing of unassigned codepoints in the input for IDN functions and do not check if the input conforms to domain name ASCII rules.
IDNA_ALLOW_UNASSIGNED (integer)
Allow processing of unassigned codepoints in the input for IDN functions.
IDNA_USE_STD3_RULES (integer)
Check if the input for IDN functions conforms to domain name ASCII rules.
IDNA_CHECK_BIDI (integer)
Check whether the input conforms to the BiDi rules. Ignored by the IDNA2003 implementation, which always performs this check.
IDNA_CHECK_CONTEXTJ (integer)
Check whether the input conforms to the CONTEXTJ rules. Ignored by the IDNA2003 implementation, as this check is new in IDNA2008.
IDNA_NONTRANSITIONAL_TO_ASCII (integer)
Option for nontransitional processing in idn_to_ascii(). Transitional processing is activated by default. This option is ignored by the IDNA2003 implementation.
IDNA_NONTRANSITIONAL_TO_UNICODE (integer)
Option for nontransitional processing in idn_to_utf8(). Transitional processing is activated by default. This option is ignored by the IDNA2003 implementation.
INTL_IDNA_VARIANT_2003 (integer)
Use IDNA 2003 algorithm in idn_to_utf8() and idn_to_ascii(). This is the default. This constant and using the default has been deprecated as of PHP 7.2.0.
INTL_IDNA_VARIANT_UTS46 (integer)
Use UTS #46 algorithm in idn_to_utf8() and idn_to_ascii(). Available as of ICU 4.6.
IDNA_ERROR_EMPTY_LABEL (integer)
IDNA_ERROR_LABEL_TOO_LONG (integer)
IDNA_ERROR_DOMAIN_NAME_TOO_LONG (integer)
IDNA_ERROR_LEADING_HYPHEN (integer)
IDNA_ERROR_TRAILING_HYPHEN (integer)
IDNA_ERROR_HYPHEN_3_4 (integer)
IDNA_ERROR_LEADING_COMBINING_MARK (integer)
IDNA_ERROR_DISALLOWED (integer)
IDNA_ERROR_PUNYCODE (integer)
IDNA_ERROR_LABEL_HAS_DOT (integer)
IDNA_ERROR_INVALID_ACE_LABEL (integer)
IDNA_ERROR_BIDI (integer)
IDNA_ERROR_CONTEXTJ (integer)
Errors reported in a bitset returned by the UTS #46 algorithm in idn_to_utf8() and idn_to_ascii().