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Solidity Programming Essentials

You're reading from   Solidity Programming Essentials A beginner's guide to build smart contracts for Ethereum and blockchain

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Product type Paperback
Published in Apr 2018
Publisher Packt
ISBN-13 9781788831383
Length 222 pages
Edition 1st Edition
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Author (1):
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Ritesh Modi Ritesh Modi
Author Profile Icon Ritesh Modi
Ritesh Modi
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Table of Contents (12) Chapters Close

Preface 1. Introduction to Blockchain, Ethereum, and Smart Contracts FREE CHAPTER 2. Installing Ethereum and Solidity 3. Introducing Solidity 4. Global Variables and Functions 5. Expressions and Control Structures 6. Writing Smart Contracts 7. Functions, Modifiers, and Fallbacks 8. Exceptions, Events, and Logging 9. Truffle Basics and Unit Testing 10. Debugging Contracts 11. Other Books You May Enjoy

The var type variables


One Solidity type that was not discussed in the last chapter is the var data type. var is a special type that can only be declared within a function. There cannot be a state variable in a contract of type var. Variables declared with the var type are known as implicitly typed variable because var does not represent any type explicitly. It informs the compiler that its type is dependent and determined by the value assigned to it the first time. Once a type is determined, it cannot be changed.

Note

The compiler decides the final data type for the var variables instead of a developer mentioning the type. It is therefore quite possible that the type determined by the block.difficulty (uint) current block compiler might not exactly be the type expected by code execution. var cannot be used with the explicit usage of memory location. An explicit memory location needs an explicit variable type.

An example of var is shown in the following screenshot. Variable uintVar8 is of type...

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