contract Helloworld
{
 string hello = “Hello World”;
 function sayHello() returns (string)
    {
        return hello;
    }
}

The code of contract goes between curly braces. The name HelloWorld is the name of our contract. It’s not necessary that the name has to be name given to the file.

The keyword contract here can be treated similar to a class in C++/java. Where class has methods and variables so are here. Let’s see.

The string variable is like a normal OOP string variable nothing fancy. The function sayHello() is a method, which when called returns something. Inside the parenthesis, goes the parameters. Currently none, but we’ll see later what they could be. The keyword returns tells us the return type of the function. Here it is string and yes it has to mentioned in parenthesis. Inside the function body we return the hello string variable.

pragma solidity ^0.8.13; 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 }