Objects & Types

Types of Objects

• https://docs.soliditylang.org/en/v0.8.13/types.html

Type	Description
uint uint8 uint16 uint32 uint64 uint256	Unsigned integer (whole number) 256 is the default if nothing is specified But it's good to be specific and use uint256 Initializes as default 0 if not assigned a value as that is the null value in Solidity Smallest is unit8 as 8 bits is a byte
int	Positive or negative whole number
bytes bytes2 bytes3 bytes5 bytes22 bytes32	bytes32 is the max size allowed bytes can have "any size"? But I think that will still limit the actual content to 32 bytes
string	Actually a type of bytes in the background, but only used for text
bool	boolean true/false
address	An address!

contract SimpleStorage {
    bool hasFavouriteNumber = true;
    uint256 favouriteNumber = 5;
    string favouriteNumberInText = "Five";
    int256 favouriteInt = -5;
    address myAddress = 0x5E666460E5BB4A8Bb14E805478176c36f3b293AB;
    bytes32 favouriteBytes = "cat";
}

Example

• https://solidity-by-example.org/primitives/

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.18;

contract Primitives {
    bool public boo = true;

    /*
    uint stands for unsigned integer, meaning non negative integers
    different sizes are available
        uint8   ranges from 0 to 2 ** 8 - 1
        uint16  ranges from 0 to 2 ** 16 - 1
        ...
        uint256 ranges from 0 to 2 ** 256 - 1
    */
    uint8 public u8 = 1;
    uint public u256 = 456;
    uint public u = 123; // uint is an alias for uint256

    /*
    Negative numbers are allowed for int types.
    Like uint, different ranges are available from int8 to int256
    
    int256 ranges from -2 ** 255 to 2 ** 255 - 1
    int128 ranges from -2 ** 127 to 2 ** 127 - 1
    */
    int8 public i8 = -1;
    int public i256 = 456;
    int public i = -123; // int is same as int256

    // minimum and maximum of int
    int public minInt = type(int).min;
    int public maxInt = type(int).max;

    address public addr = 0xCA35b7d915458EF540aDe6068dFe2F44E8fa733c;

    /*
    In Solidity, the data type byte represent a sequence of bytes. 
    Solidity presents two type of bytes types :

     - fixed-sized byte arrays
     - dynamically-sized byte arrays.
     
     The term bytes in Solidity represents a dynamic array of bytes. 
     It’s a shorthand for byte[] .
    */
    bytes1 a = 0xb5; //  [10110101]
    bytes1 b = 0x56; //  [01010110]

    // Default values
    // Unassigned variables have a default value
    bool public defaultBoo; // false
    uint public defaultUint; // 0
    int public defaultInt; // 0
    address public defaultAddr; // 0x0000000000000000000000000000000000000000
}