Book Image

Blockchain Developer's Guide

By : Brenn Hill, Samanyu Chopra, Paul Valencourt, Narayan Prusty
Book Image

Blockchain Developer's Guide

By: Brenn Hill, Samanyu Chopra, Paul Valencourt, Narayan Prusty

Overview of this book

Blockchain applications provide a single-shared ledger to eliminate trust issues involving multiple stakeholders. It is the main technical innovation of Bitcoin, where it serves as the public ledger for Bitcoin transactions. Blockchain Developer's Guide takes you through the electrifying world of blockchain technology. It begins with the basic design of a blockchain and elaborates concepts, such as Initial Coin Offerings (ICOs), tokens, smart contracts, and other related terminologies. You will then explore the components of Ethereum, such as Ether tokens, transactions, and smart contracts that you need to build simple DApps. Blockchain Developer's Guide also explains why you must specifically use Solidity for Ethereum-based projects and lets you explore different blockchains with easy-to-follow examples. You will learn a wide range of concepts - beginning with cryptography in cryptocurrencies and including ether security, mining, and smart contracts. You will learn how to use web sockets and various API services for Ethereum. By the end of this Learning Path, you will be able to build efficient decentralized applications. This Learning Path includes content from the following Packt products: • Blockchain Quick Reference by Brenn Hill, Samanyu Chopra, Paul Valencourt • Building Blockchain Projects by Narayan Prusty
Table of Contents (37 chapters)
Title Page
Copyright
About Packt
Contributors
Preface
Index

Data location


All programming languages you would have learned so far store their variables in memory. But in Solidity, variables are stored in the memory and the filesystem depending on the context.

Depending on the context, there is always a default location. But for complex data types, such as strings, arrays, and structs, it can be overridden by appending either storage or memory to the type. The default for function parameters (including return parameters) is memory, the default for local variables is storage. and the location is forced to storage, for state variables (obviously).

Data locations are important because they change how assignments behave:

  • Assignments between storage variables and memory variables always create an independent copy. But assignments from one memory-stored complex type to another memory-stored complex type do not create a copy.
  • Assignment to a state variable (even from other state variables) always creates an independent copy.
  • You cannot assign complex types stored...