Book Image

Solidity Programming Essentials

Book Image

Solidity Programming Essentials

Overview of this book

Solidity is a contract-oriented language whose syntax is highly influenced by JavaScript, and is designed to compile code for the Ethereum Virtual Machine. Solidity Programming Essentials will be your guide to understanding Solidity programming to build smart contracts for Ethereum and blockchain from ground-up. We begin with a brief run-through of blockchain, Ethereum, and their most important concepts or components. You will learn how to install all the necessary tools to write, test, and debug Solidity contracts on Ethereum. Then, you will explore the layout of a Solidity source file and work with the different data types. The next set of recipes will help you work with operators, control structures, and data structures while building your smart contracts. We take you through function calls, return types, function modifers, and recipes in object-oriented programming with Solidity. Learn all you can on event logging and exception handling, as well as testing and debugging smart contracts. By the end of this book, you will be able to write, deploy, and test smart contracts in Ethereum. This book will bring forth the essence of writing contracts using Solidity and also help you develop Solidity skills in no time.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Cryptography global variables


Solidity provides cryptographic functions for hashing values within contract functions. There are two hashing functions—SHA2 and SHA3.

The sha3 function converts the input into a hash based on the sha3 algorithm while sha256 converts the input into a hash based on the sha2 algorithm. There is another function, keccak256, which is an alias of the SHA3 algorithm. It is recommended to use the keccak256 or sha3 functions for hashing needs.

The following screenshot of the code segment illustrates this:

The result of executing this function is shown in the following screenshot. The result of both the keccak256 and sha3 functions is the same:

All three of these functions work on tightly packed arguments, meaning that multiple parameters can be concatenated together to find a hash, as shown in the following code snippet:

keccak256(97, 98, 99)