Solidity

Variables and types

• Local
• Declared inside a function and are not stored on blockchain

• State
• Declared outside a function to maintain the state of the smart contract
• Stored on the blockchain

• Global
• Provide information about the blockchain. They are injected by the Ethereum

Functions, Arrays, Strings, Loops and If/Else

// Define the compiler version you would be using
pragma solidity ^0.8.10;

// Start by creating a contract named Conditions
contract Conditions {
    // State variable to store a number
    uint public num;
		// Array can have a compile-time fixed size or a dynamic size.
		string public greet = "Hello World!";
		uint[] public arr;
    uint[] public arr2 = [1, 2, 3];
    // Fixed sized array, all elements initialize to 0
    uint[10] public myFixedSizeArr;
    // Memory variables and Storage variables can be thought of as similar to RAM vs Hard Disk.
    // Memory variables exist temporarily, during function execution, whereas Storage variables
    // are persistent across function calls for the lifetime of the contract.
    // Here the array is only needed for the duration while the function executes and thus is declared as a memory variable
		function getArr(uint[] memory _arr) public view returns (uint[] memory) {
        return _arr;
    }

    /*
        Name of the function is set.
        It takes in an uint and sets the state variable num.
        It is declared as a public function meaning
        it can be called from within the contract and also externally.
    */
    function set(uint _num) public {
        num = _num;
    }

    /*
        Name of the function is get.
        It returns the value of num.
        It is declared as a view function meaning
        that the function doesn't change the state of any variable.
        view functions in solidity do not require gas.
    */
    function get() public view returns (uint) {
        return num;
    }

    /*
        Name of the function is foo.
        It takes in an uint and returns an uint.
        It compares the value of x using if/else
    */
    function foo(uint x) public returns (uint) {
        if (x < 10) {
            return 0;
        } else if (x < 20) {
            return 1;
        } else {
            return 2;
        }
    }

    /*
        Name of the function is loop.
        It runs a loop till 10
    */
    function loop() public {
        // for loop
        for (uint i = 0; i < 10; i++) {
            if (i == 3) {
                // Skip to next iteration with continue
                continue;
            }
            if (i == 5) {
                // Exit loop with break
                break;
            }
        }
    }


}