[Solidity] How to write comparison operators (equal/not equal)?

This section explains how to write comparison operators (equal/not equal) in Solidity.

Syntax

The following is how to write comparison operators (equal/not equal) in Solidity.

Equal (equivalent)

"Equal (equivalent)" is written with == followed by two equals (=).

value 1 == value 2

Not Equal (inequivalent)

"Not equal (inequivalent)" is indicated by ! = and exclamation mark (!) and an equal (=) is written.

value 1 != value 2

To combine multiple conditions

To group multiple conditions together, enclose the clusters of conditions in parentheses (()).

(value 1 == value 2) && (value 3 != value 4)

Sample Code

// SPDX-License-Identifier: GPL-3.0
 
pragma solidity >=0.7.0 <0.9.0;

contract Test {
    
    function evenOrOdd(uint num) public pure returns(string memory) {
        string memory message = "";

        // The remainder of 2 dividing num is zero
        if (num % 2 == 0) {
            message = "even"; 
        }

        // The remainder of 2 dividing num is not zero
        if (num % 2 != 0) {
            message = "odd";
        }

        return message;
    }

}