Yashotantra Academy logo
← Solidity theorytheory 0/50 · 0%
level 1
Curious · 0 XP
streak
0d
perfect
0
badges
0

100 XP to Apprentice

Value · easy

16. Sending and receiving ETH

receive, fallback, transfer and call.

1 min read3 questionsup to 50 XPtopic 16/50

Read in another language

AI translates the explanation and quiz text while preserving code and answer scoring.

A contract can accept plain ETH transfers only if it has a `receive()` or a payable `fallback()`. To send, prefer `call` with an explicit success check, since `transfer` forwards a fixed 2300 gas that can break with smart-contract wallets.

solidity
receive() external payable {}

function payOut(address to, uint256 amount) internal {
    (bool ok, ) = to.call{value: amount}("");
    require(ok, "send failed");
}

Always write state before sending value, and check the returned boolean.

How to study this topic

  1. 1. Read the explanation once end to end, skipping the code.
  2. 2. Re-read the code snippets and say out loud what each line does.
  3. 3. Answer the quiz without scrolling back — that is the real check.
  4. 4. Read every explanation, even for the answers you got right.

Scoring

  • · Up to 30 XP from quiz accuracy.
  • · +15 XP for a perfect first attempt.
  • · +5 XP while a 3-day streak is running.
  • · 75% or higher marks the topic complete.

Check your understanding

  1. 1. Which function receives plain ETH with empty calldata?

  2. 2. Why prefer `call{value:}` over `transfer`?

  3. 3. What must you do with `call`'s return value?

Badges

First light
Pass your first topic
Sharp shooter
3 perfect first-try quizzes
On a roll
Study 3 days in a row
Week warrior
Study 7 days in a row
Grinder
Earn 500 XP
Deep diver
Earn 1500 XP