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payable function
Learn payable function in Solidity through a focused explanation, a dedicated construct-specific example, an engineering boundary, and a mastery check.
payable function is an atomic Solidity topic inside Functions. This lesson focuses on how the payable function construct is written, what it changes, and when it is the right tool.
Trace the example line by line. Identify the exact syntax for payable function, 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
contract Tip { function tip() external payable { require(msg.value>0,'zero tip'); } }
For payable function, 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.