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Contracts & Types
Contract declaration State variable Local variable uint types int types bool address bytes string enum
Functions
public function external function internal function private function view function pure function payable function returns function overloading named return variables
Data Locations
storage memory calldata storage reference memory copy dynamic array fixed array mapping nested mapping struct
Control & Errors
if else for loop while loop require revert assert custom error try catch unchecked block ternary expression
Ether & Calls
msg.sender msg.value address balance transfer send call staticcall delegatecall receive function fallback function
Events & Modifiers
event indexed event parameter emit modifier modifier arguments multiple modifiers constructor immutable constant receive event logging
Inheritance & Interfaces
inheritance virtual override super abstract contract interface interface call library using for multiple inheritance
Security & Advanced
checks effects interactions reentrancy guard access control pull payment block.timestamp block.number keccak256 abi.encode abi.encodePacked selfdestruct caveat
Solidity / Data Locations

mapping

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

10 min read • Beginner

mapping is an atomic Solidity topic inside Data Locations. This lesson focuses on how the mapping construct is written, what it changes, and when it is the right tool.

Trace the example line by line. Identify the exact syntax for mapping, 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-03-08-mapping.sol
solidity Try It Live 
contract C { mapping(address=>uint) public balances; function credit(uint n) external { balances[msg.sender]+=n; } }
Edge case / engineering note

For mapping, 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

mapping Mastery Check →
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fixed array
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nested mapping