Functions in solidity

function in javascript

function add(x, y) {
  return x + y;
}

function in solidity

function add(uint256 x, uint256 y) public pure returns(uint256) {
    return x + y;
}

Similarities between two functions

• Both has function keyword

Let's look what are the differences between them:

• first of all we can see returns keyword and inside the parenthesis data type of return value.

• Second thing to notice is that in arguments in solidity has it's data types also

Let's breakdown function in solidity

• function keyword
• public keyword
• returns (uint256)
• pure function type

function keyword is used to declared a function.

public is the visibility of the function (from where this function can be called).

returns keyword is telling that this function returns a value and uint256 is the data type of value

Why parenthesis on (uint256)? This has parenthesis because a function can returns multiple values in a tupple (in parenthesis.)

There are two more keyword you can see in function which are function type keyword

• view
• pure

view - Function only reading variables from the contract but not changing it's values. Read only.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
contract Example {
    uint public counter = 20;
 
    function addFive() public view returns(uint){
        return counter + 5;
    }
}

pure - Function neither read variables from the contract nor chages variable values. It does not touch contract variables nor see.

function double(uint256 x) public pure returns(uint256){
    return 2 * x;
}

How do I return multiple values? You can return multiple values from function in tupple (inside parenthesis).

function getSumAndMul(uint256 x, uint256 y) public pure returns(uint256, uint256){
    return (x+y, x*y)
}

Do you know you can declare function with same name with different argument solidity will not complain?

let's see how?

function add(uint256 x, uint256y) public pure returns(uint256){
    return x + y;
}
function add(uint256 x, uint256y, uint256 z) public pure returns(uint256){
    return x + y + z;
}

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