# Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

The following constants indicate the type of error returned by json_last_error() or stored as the code of a JsonException.

`JSON_ERROR_NONE` (int)
  No error has occurred. Available as of PHP 5.3.0.
`JSON_ERROR_DEPTH` (int)
  The maximum stack depth has been exceeded. Available as of PHP 5.3.0.
`JSON_ERROR_STATE_MISMATCH` (int)
  Occurs with underflow or with the modes mismatch. Available as of PHP 5.3.0.
`JSON_ERROR_CTRL_CHAR` (int)
  Control character error, possibly incorrectly encoded. Available as of PHP 5.3.0.
`JSON_ERROR_SYNTAX` (int)
  Syntax error. Available as of PHP 5.3.0.
`JSON_ERROR_UTF8` (int)
  Malformed UTF-8 characters, possibly incorrectly encoded. Available as of PHP 5.3.3.
`JSON_ERROR_RECURSION` (int)
  The object or array passed to json_encode() include recursive references and cannot be encoded. If the `JSON_PARTIAL_OUTPUT_ON_ERROR` option was given, `NULL` will be encoded in the place of the recursive reference. Available as of PHP 5.5.0.
`JSON_ERROR_INF_OR_NAN` (int)
  The value passed to json_encode() includes either `NAN` or `INF`. If the `JSON_PARTIAL_OUTPUT_ON_ERROR` option was given, `0` will be encoded in the place of these special numbers. Available as of PHP 5.5.0.
`JSON_ERROR_UNSUPPORTED_TYPE` (int)
  A value of an unsupported type was given to json_encode(), such as a resource. If the `JSON_PARTIAL_OUTPUT_ON_ERROR` option was given, `NULL` will be encoded in the place of the unsupported value. Available as of PHP 5.5.0.
`JSON_ERROR_INVALID_PROPERTY_NAME` (int)
  A key starting with \u0000 character was in the string passed to json_decode() when decoding a JSON object into a PHP object. Available as of PHP 7.0.0.
`JSON_ERROR_UTF16` (int)
  Single unpaired UTF-16 surrogate in unicode escape contained in the JSON string passed to json_decode(). Available as of PHP 7.0.0.

The following constants can be combined to form options for json_decode().

`JSON_BIGINT_AS_STRING` (int)
  Decodes large integers as their original string value. Available as of PHP 5.4.0.
`JSON_OBJECT_AS_ARRAY` (int)
  Decodes JSON objects as PHP array. This option can be added automatically by calling json_decode() with the second parameter equal to `TRUE`. Available as of PHP 5.4.0.

The following constants can be combined to form options for json_encode().

`JSON_HEX_TAG` (int)
  All < and > are converted to \u003C and \u003E. Available as of PHP 5.3.0.
`JSON_HEX_AMP` (int)
  All & are converted to \u0026. Available as of PHP 5.3.0.
`JSON_HEX_APOS` (int)
  All ' are converted to \u0027. Available as of PHP 5.3.0.
`JSON_HEX_QUOT` (int)
  All " are converted to \u0022. Available as of PHP 5.3.0.
`JSON_FORCE_OBJECT` (int)
  Outputs an object rather than an array when a non-associative array is used. Especially useful when the recipient of the output is expecting an object and the array is empty. Available as of PHP 5.3.0.
`JSON_NUMERIC_CHECK` (int)
  Encodes numeric strings as numbers. Available as of PHP 5.3.3.
`JSON_PRETTY_PRINT` (int)
  Use whitespace in returned data to format it. Available as of PHP 5.4.0.
`JSON_UNESCAPED_SLASHES` (int)
  Don't escape `/`. Available as of PHP 5.4.0.
`JSON_UNESCAPED_UNICODE` (int)
  Encode multibyte Unicode characters literally (default is to escape as \uXXXX). Available as of PHP 5.4.0.
`JSON_PARTIAL_OUTPUT_ON_ERROR` (int)
  Substitute some unencodable values instead of failing. Available as of PHP 5.5.0.
`JSON_PRESERVE_ZERO_FRACTION` (int)
  Ensures that float values are always encoded as a float value. Available as of PHP 5.6.6.
`JSON_UNESCAPED_LINE_TERMINATORS` (int)
  The line terminators are kept unescaped when `JSON_UNESCAPED_UNICODE` is supplied. It uses the same behaviour as it was before PHP 7.1 without this constant. Available as of PHP 7.1.0.

The following constants can be combined to form options for json_decode() and json_encode().

`JSON_INVALID_UTF8_IGNORE` (int)
  Ignore invalid UTF-8 characters. Available as of PHP 7.2.0.
`JSON_INVALID_UTF8_SUBSTITUTE` (int)
  Convert invalid UTF-8 characters to \0xfffd (Unicode Character 'REPLACEMENT CHARACTER') Available as of PHP 7.2.0.
`JSON_THROW_ON_ERROR` (int)
  Throws JsonException if an error occurs instead of setting the global error state that is retrieved with json_last_error() and json_last_error_msg(). `JSON_PARTIAL_OUTPUT_ON_ERROR` takes precedence over `JSON_THROW_ON_ERROR`. Available as of PHP 7.3.0.