What is Solidity?
Solidity is an object-oriented programming language for writing smart contracts. It is a high-level language for implementing smart contracts. It is the primary language for writing smart contracts in the Ethereum Blockchain.
What is a Smart Contract?
A smart contract is a program or a piece of code that governs and controls actions within the blockchain.
To practice some Solidity basics, we are going to use the Remix IDE. Remix is an online open-source IDE that allows us to write and deploy our smart contracts.
If you are a beginner and this is your first time trying the solidity language, don't worry this guide is also for you. As long as you have programming knowledge you are good to go. Even if you don't, you are also good to go.
pragma solidity 0.8.11;
contract MyContract {
uint8 public storedNumber;
function changeNumber(uint8 newNumber) public {
require(storedNumber != newNumber, "They are the same number")
storedNumber = newNumber
}
function getCurrentNumber() public pure returns(uint8) {
return storedNumber;
}
}
This is what a smart contract looks like.
Now let's get some fundamentals.
Solidity Data Types
Data types are classifications or types which tell the computer how we want to use the data.
1. Boolean
The bool data type is used to represent situations that have binary results, such as 1 or 0, true or false. The 0 is false and the 1 is true.
The Solidity language supports both logical and comparison operators.
Logical
! Logical Negation
&& And
|| OR
Comparison
== equality
!= inequality
pragma solidity 0.8.11;
contract MyBool {
bool public isSet = True;
bool public isPresent = False;
}
2. Bitwise Operators
& And
| OR
^ XOR
~ Bitwise negation
<< Left Shift
>> Right Shift
3. Arithmetic Operators
+ Addition
- Subtraction
* Multiplication
/ Division
% Modulo
Value Types in Solidity
1. Addresses
Addresses in solidity hold a 20-byte value which represents the size of an Ethereum address. An address is a unique public key that points to a wallet where assets can be stored.
pragma solidity ^0.8.1;
contract FirstProgram {
address public walletAddress = "0x2Dc85851940eC853f63587c45751126E1877d8C0";
}
2. Enums
enums or enumerable in solidity are used to create user-defined data types. It restricts the variable to only one of the pre-defined values.
Enums allow the contract more readable, and maintainable. it also reduces the errors in the contract.
pragma solidity ^0.8.1;
contract MyFirst {
enum Switch {
ON,
OFF
};
Switch switch;
function onSwitch() public{
switch = Switch.ON;
}
function offSwitch() public {
switch = Switch.OFF;
}
function switchReturn() public view returns(Switch) {
return Switch;
}
}
Reference Types in Solidity
4. Arrays
An array is a collection of elements of the same data type which can be identified using their location called index.
An array can either be dynamic or fixed.
address[] addresses
uint256[] myArray
function add() internal {
myArray.push(123);
}
Example of Dynamic array and fixed array
uint256[] dynamicArrays;
uint256[5] fixedArrays;
5. Struct
Struct allows us to create more complicated data types and define our own type in form of structures.
struct people {
string name;
uint256 favoriteColor;
uint256 age;
}
6. Mapping
Mapping is similar to Dictionary or Hash tables in other languages. It accepts a key type and value type pair.
Mapping Syntax
mapping(key_type => value_type) mappingName;
struct people {
string name;
uint256 favoriteColor;
uint256 age;
}
mapping(address => people) bio;
address[] public people_bio;
Conclusion
In this article, we discussed Solidity and its data types, value types, and reference types. We also explained what smart contracts are and how they are connected to solidity.
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