Memory Type Variable in Ethereum Solidity

When it is necessary to store return value of a function into a memory type variable in smart contract, the size of memory type variable should be declared before storing data

https://medium.com/coinmonks/ethereum-solidity-memory-vs-storage-which-to-use-in-local-functions-72b593c3703a

https://solidity.readthedocs.io/en/v0.4.24/types.html