In this Article, We will explain these topics:-

• Value Types        
• Variables Types
• Function
• View and Pure Functions
• Visibility        
• Function Modifier

Value Types:

Here we introduce you to some primitive data types available in Solidity.

• • Bool
  • int
  • uint
  • address
  • Bytes32

 // Default values

bool public defaultBool; // false
uint public defaultUint; // 0
int public defaultInt; // 0

Functions:

The basic syntax is shown here.

function function-name(parameter-list) scope returns() {
   //statements
}

contract Function {
    // Functions can return multiple values.
    function returnMany() public pure returns (uint, bool, uint) {
        return (1, true, 2);
    }
   // Return values can be named.
    function named() public pure returns (uint x, bool b, uint y) {
        return (1, true, 2);
   }

View and Pure Functions:

There are various types of Solidity functions we’ll be covering (View and Pure Functions)

1. View functions: are read-only function, which ensures that state variables cannot be modified after calling them. By default, a get method is view function
   • Do not modify state
2. Pure functions:  do not read or modify the state variables, which returns the values only using the parameters passed to the function or local variables present in it. If the statements which read the state variables, access the address or balance, access any global variable block or msg, call a function that is not pure

• • Do not modify state
  • Do not read state

Example

Visibility :

Functions and state variables have to declare whether they are accessible by other contracts.

Functions can be declared as

• public – any contract and account can call
• private – only inside the contract that defines the function
• internal– only inside contract that inherits an internal function
• external – only other contracts and accounts can call

NOTE: State variables can be declared as public, private, or internal but not external.

Function Modifier:

Function Modifiers are used to modify the behavior of a function. For example to add a prerequisite to a function.

Modifiers are

• Reusable code
• Run before and/or after a function call.

Modifiers can be used to:

• Restrict access
• Validate inputs
• Guard against reentrancy hack