Solidity Concepts for Contract Development BDC Practice Questions (Page 1)

Questions 1–5

1. 1foundation · easy

   Which function modifier is required for a Solidity function to be able to receive Ether?

   • Ainternal
   • Bview
   • Cpayable
   • Dpure
   Reveal Solution Discussion Select an answer first
2. 2application · medium

   A contract has a function that should only be called by the contract owner. The developer wants to ensure that the function cannot be called by other contracts or externally. Which visibility and modifier combination is appropriate?

   • Aprivate with an onlyOwner modifier.
   • Bexternal with an onlyOwner modifier.
   • Cinternal with an onlyOwner modifier.
   • Dpublic with an onlyOwner modifier.
   Reveal Solution Discussion Select an answer first
4. 3foundation · easy

   Which Solidity function is the recommended way to transfer Ether from a contract to an address?

   • AsendTransaction
   • Bcall
   • Ctransfer
   • Dsend
   Reveal Solution Discussion Select an answer first
5. 4foundation · easy

   Which security pattern involves updating the contract's state before making external calls to prevent reentrancy attacks?

   • AChecks-Effects-Interactions
   • BDefense in depth
   • CLeast privilege
   • DFail early and fail loud
   Reveal Solution Discussion Select an answer first
6. 5expert · medium

   A developer is optimizing a function that processes a large array of structs stored in storage. The function needs to read and modify each struct. To minimize gas, what is the best approach?

   • AUse calldata for the array and modify it in place.
   • BIterate over the array in storage and modify each struct in place.
   • CUse a mapping instead of an array to avoid iteration.
   • DLoad the entire array into memory, modify it, and then write it back to storage.
   Reveal Solution Discussion Select an answer first