Ethereum Cookbook

How to do it...

1. State variables are always stored in storage, and function arguments are always in memory.

2. The memory location of a variable can be explicitly specified with the storage or memory keywords:

uint storage sum;uint memory calc;

3. Local variables created for struct, array, or mapping types always reference storage by default. Modifying this local variable changes the actual storage data:

pragma solidity ^0.4.22;contract Storage {    struct Name {        string fName;        string lName;    }    mapping(address => Name) public names;    function setName(string _fName,string _lName) public {        // Declared as a storage pointer        Name n = names[msg.sender];        // Modifies state variable        n.fName = _fName;        n.lName = _lName;    }}

4. Variables can be declared as ...