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Contract declaration State variable Local variable uint types int types bool address bytes string enum
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inheritance virtual override super abstract contract interface interface call library using for multiple inheritance
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checks effects interactions reentrancy guard access control pull payment block.timestamp block.number keccak256 abi.encode abi.encodePacked selfdestruct caveat
Solidity / Contracts & Types

Contract declaration

Learn Contract declaration in Solidity through a focused explanation, a dedicated construct-specific example, an engineering boundary, and a mastery check.

10 min read • Beginner

Contract declaration is an atomic Solidity topic inside Contracts & Types. This lesson focuses on how the Contract declaration construct is written, what it changes, and when it is the right tool.

Trace the example line by line. Identify the exact syntax for Contract declaration, the input state before it runs, and the resulting value, control flow, database state, hardware behavior, or runtime effect afterward. Neighboring lessons use different constructs rather than renamed copies of this one.

Topic-specific example

solidity-01-01-contract-declaration.sol
solidity Try It Live 
contract Counter { uint256 public value; }
Edge case / engineering note

For Contract declaration, test the boundary that belongs to this exact feature rather than a generic failure case. Check invalid or empty input, NULL/unknown state, numeric limits, transaction or exception behavior, synthesis/runtime constraints, ownership/permission rules, or backtracking/control-flow effects where they apply.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

Contract declaration Mastery Check →
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State variable