Book Image

Building Blockchain Projects

By : Narayan Prusty
Book Image

Building Blockchain Projects

By: Narayan Prusty

Overview of this book

Blockchain is a decentralized ledger that maintains a continuously growing list of data records that are secured from tampering and revision. Every user is allowed to connect to the network, send new transactions to it, verify transactions, and create new blocks, making it permission-less. This book will teach you what blockchain is, how it maintains data integrity, and how to create real-world blockchain projects using Ethereum. With interesting real-world projects, you will learn how to write smart contracts which run exactly as programmed without any chance of fraud, censorship, or third-party interference, and build end-to-e applications for blockchain. You will learn about concepts such as cryptography in cryptocurrencies, ether security, mining, smart contracts, solidity, and more. You will also learn about web sockets, various API services for Ethereum, and much more. The blockchain is the main technical innovation of bitcoin, where it serves as the public ledger for bitcoin transactions.
Table of Contents (10 chapters)

Solidity source files


A Solidity source file is indicated using the .sol extension. Just like any other programming language, there are various versions of Solidity. The latest version at the time of writing this book is 0.4.2.

In the source file, you can mention the compiler version for which the code is written for using the pragma Solidity directive.

For example, take a look at the following:

pragma Solidity ^0.4.2; 

Now the source file will not compile with a compiler earlier than version 0.4.2, and it will also not work on a compiler starting from version 0.5.0 (this second condition is added using ^). Compiler versions between 0.4.2 to 0.5.0 are most likely to include bug fixes instead of breaking anything.

Note

It is possible to specify much more complex rules for the compiler version; the expression follows those used by npm.