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

The fallback function


The fallback functions are a special type of function available only in Ethereum. Solidity helps in writing fallback functions. Imagine a situation where you, as a Solidity developer, are consuming a smart contract by invoking its functions. It is quite possible that you use a function name that does not exist within that contract. In such cases, the fallback function, as the name suggests, would automatically be invoked.

A fallback function is invoked when no function name matches the called function.

A fallback function does not have an identifier or function name. It is defined without a name. Since it cannot be called explicitly, it cannot accept any arguments or return any value. An example of a fallback function is as follows:

A fallback function can also be invoked when a contract receives any Ether. This usually happens using the SendTransaction function available in web3 to send Ether from one account to a contract. However, in this case, the fallback function...