# 枚舉 枚舉類型是在Solidity中的一種用戶自定義類型。他可以顯示的轉換與整數進行轉換，但不能進行隱式轉換。顯示的轉換會在運行時檢查數值范圍，如果不匹配，將會引起異常。枚舉類型應至少有一名成員。我們來看看下面的例子吧。 ``` pragma solidity ^0.4.0; contract test { enum ActionChoices { GoLeft, GoRight, GoStraight, SitStill } ActionChoices choice; ActionChoices constant defaultChoice = ActionChoices.GoStraight; function setGoStraight() { choice = ActionChoices.GoStraight; } // Since enum types are not part of the ABI, the signature of "getChoice" // will automatically be changed to "getChoice() returns (uint8)" // for all matters external to Solidity. The integer type used is just // large enough to hold all enum values, i.e. if you have more values, // `uint16` will be used and so on. function getChoice() returns (ActionChoices) { return choice; } function getDefaultChoice() returns (uint) { return uint(defaultChoice); } } ```