Lesson-9: Need a code explanation

[Vanshika0901]

need a code explanation for line number 74

[adityabhattad2021]

So in this line of code

(bool success, ) = recentWinner.call{value: address(this).balance}("");

In this line address(this).balance we check the total amount of ETH present in the contract (Sent by the players as entry fees to the contract
so we can do

uint256 totalContractBalance=address(this).balance;
(bool success, ) = recentWinner.call{value: totalContractBalance}("");

here bool success will store true or false based on whether transection was successful or not.
recentWinner.call in this line we are specifying whom to sent the amount to.
just an example (some address).call{value:amt} here the amt will be sent to some address
("") with this at the end we can basically send a message, we are sending empty string hence no message.

Edit: Changed return to store.

[krakxn]

The above answer is partially wrong, and as so I will dissect—for concision—it in parts.

(bool success, ) stores the value of either true or false, depending on what the right-hand side to the = operator evaluates to.

recentWinner.call this results in the call keyword being used. Put simply, think of it as a "transferring money" keyword. So, we are transferring money to recentWinner's address, not "some address".

call{value: totalContractBalance} call takes in a value, which specifies the above quantity of the "money"

("") this is just a message, as to which we do not assign any, i.e an empty string. Hence, no message. BTW, this is used in advanced demonstrations usually.

[Vanshika0901]

thank you so much

[adityabhattad2021]

Oh @krakxn thanks for correcting my answer.
But just an example (some address).call{value:amt} here the amt will be sent to some address was just an example to convey that
whatever address we specify here <address>.call{value:amt} that amt will be transferred to that address.
Is that incorrect?

[Vanshika0901]

can you also help me in solving this errors

[adityabhattad2021]

You are getting this error because there are some functions you need to implement in your contract from the inherited contract, in you case VRFConsumerBaseV2, don't worry that error will go away when you implement those functions. Follow along with the video, patrick does implements those functions later.

[krakxn]

@adityabhattad2021 That is fine.

@Vanshika0901 That is just problems diagnosed on compile-time; when the Solidity compiler scans through the entire source-code—to convert the source-code into machine code—and as a result will be fixed when you are done fixing the contract. If not, that indicates there are some errors in the code.