View and pure functions

 Introduction to view functions

View function has the following features:

• Display the data.
• Do not modify the state variable,
• Are good for reading data operations
• Only reads but doesn’t modify the variables of the state.

Introduction to pure functions

Pure functions have the following features:

• Do not access data from the blockchain
• Do not allow to read or write operations
• No access to state data or transaction data
• Return type based on the data from a function

View and Pure Example:

In the below example, “sumX” is a view function and it can read values from the blockchain whereas the function “sumI” is a pure function which is just used for smart contract level calculations and it neither reads nor writes data to the blockchain

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.13;

contract ViewPure {

    uint public x = 1;

    // Promise not to modify the state.

    function sumX(uint y) public view returns (uint) {

        return x + y;

    }

    // Promise not to modify or read from the state.

    function sumI(uint i, uint j) public pure returns (uint) {

        return i + j;

    }

}