ArslanKathia

// SPDX-License-Identifier: MIT
pragma solidity ^0.8;

contract ownable{
    address public owner;

    constructor(){
        owner = msg.sender;
    }
    

ArslanKathia

// SPDX-License-Identifier: MIT

pragma solidity ^0.8;

//data type & value type - references
contract valueType{
    bool public boolTemp = true;

    uint public temp = 2335;

ArslanKathia

// SPDX-License-Identifier: MIT

pragma solidity ^0.8;

contract funcIntro{

    uint age;
    
    function add(uint _x,uint _y) public pure returns(uint){
        return _x + _y;

ArslanKathia

// SPDX-License-Identifier: MIT

pragma solidity ^0.8;

contract stateVariable{
    //state variable which is defined in contract but used outside of the functions
    //state variable stored on blockchain block storage so we can't create extra state variable bcz its cost gas
    uint public salary;
    
    constructor(){

ArslanKathia

// SPDX-License-Identifier: MIT
pragma solidity ^0.8;

contract localVariable{
    //local variable created in functions that are local
    //when function work is done that local variable work washout from RAM as well
    uint public age;
    bool public b;
    address public addr;

ArslanKathia

//SPDX-License-Identifier: MIT

pragma solidity ^0.8;

contract gloablVariable{
    //predefined variable used in workspace is global variable 
    address public addr =  msg.sender;
    uint public timestamp =  block.timestamp;
    uint public diff = block.difficulty;
    uint public gasprice = tx.gasprice;

ArslanKathia

// SPDX-License-Identifier: MIT

pragma solidity ^0.8;

contract viewAndPureFunctions{
    uint public age;

    constructor(){
        age =20;
    }

ArslanKathia

// SPDX-License-Identifier: MIT

pragma solidity ^0.8;

contract defaultValue{
    uint public x;
    bool public y;
    string public str;
    address public addr;
    bytes32 public b32;

ArslanKathia

// SPDX-License-Identifier: MIT

pragma solidity ^0.8;

contract _string{

    string public str= "gateway";  //state variable

    //constant keyword variable charge lower gas than other variable
    address public constant ownerAddress = 0x5B38Da6a701c568545dCfcB03FcB875f56beddC4;  //lower gas cost

ArslanKathia

//SPDX-License-Identifier: MIT

pragma solidity ^0.8;

contract CONSTRUCTOR{
    //contract level
    /**
    inside the contract and outside of function
    **/
    uint public age;