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What are enums in Solidity?
Shubham Singh KshatriyaIn Solidity, enums stand for Enumerable. Enums are user-defined data types that restrict the variable to have only one of the predefined values.
The predefined values present in the enumerated list are called enums. Internally, enums are treated as numbers. Solidity automatically converts the enums to unsigned integers.
An enum should have at least one value in the enumerated list. This value cannot be a number (positive or negative) or a boolean value (true or false).
Syntax
enum <enum-name> {
value1,
value2,
...
}
Code
In the code snippet below, we will see how we can create an enum in Solidity.
pragma solidity ^0.5.0;
contract Example {
// creating an enum
enum Button { ON, OFF }
// declaring a variable of type enum
Button button;
// function to turn on the button
function buttonOn() public {
// set the value of button to ON
button = Button.ON;
}
// function to turn off the button
function buttonOff() public {
// set the value of button to OFF
button = Button.OFF;
}
// function to get the value of the button
function getbuttonState() public view returns(Button) {
// return the value of button
return button;
}
}Creating an example enum
Explanation
- Line 3: We create a contract named
Example. - Line 5: We create an enum named
Button. - Line 8: We declare a variable
buttonof theenumtype. - Line 11: We create a function
buttonOn()to turn on the button. - Line 16: We create another function,
buttonOff()to turn off the button. - Line 21: We create a third button,
getButtonState()to get the value of the button.
Output
- When we call the
buttonOn()function, the value of the button will be set toButton.ON. - When we call the
buttonOff()function, the value of the button will be set toButton.OFF. - When we call the
getButtonState()function, the value of the button will be returned.
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