# 预定义常量

下列常量由此扩展定义，且仅在此扩展编译入 PHP 或在运行时动态载入时可用。

`YAR_VERSION` (string)
`YAR_CLIENT_PROTOCOL_HTTP` (int)
`YAR_OPT_PACKAGER` (int)
`YAR_OPT_TIMEOUT` (int)
`YAR_OPT_CONNECT_TIMEOUT` (int)
`YAR_OPT_HEADER` (array)
  自 2.0.4 起
`YAR_PACKAGER_PHP` (string)
`YAR_PACKAGER_JSON` (string)
`YAR_ERR_OKEY` (int)
`YAR_ERR_OUTPUT` (int)
`YAR_ERR_TRANSPORT` (int)
`YAR_ERR_REQUEST` (int)
`YAR_ERR_PROTOCOL` (int)
`YAR_ERR_PACKAGER` (int)
`YAR_ERR_EXCEPTION` (int)

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