Vyper Data Types (Series 2)

Previously, we discussed why Vyper is a game changer as it is one of the fastest growing smart contract development languages.

We also covered some basics like Pragma and Constructor. You can read it here.

Today we’ll take a deep dive into data types and how they work.

What are data types?

Data types help us organize different information in our code, just like we sort items into specific locations at home.

These types are set before the program is run. Just like a container designed for liquids is not suitable for storing solids, each variable in Vyper can only store the data type for which it was designed.

When writing code, we need to specify what data type each variable will hold - whether it's a number for calculations, text for a name, or true/false for simple decisions. These types ensure that our programs handle information correctly, preventing errors such as trying to multiply someone's name or add letters together.

Understanding data types in Vyper

• Boolean - simple true/false

Think of Boolean values ​​like light switches - they can only be in two states: true or false. We use them in our code to make yes/no decisions.

<code>is_active: bool = True
is_paused: bool = False

# 可以翻转布尔值
is_active = not is_active  # 现在是 False</code>

Certain operators can be used effectively with boolean values, including not, or == and !=. This means we can use them to prove truth or falsehood.

**运算符**	**描述**
not x	逻辑否定
x and y	逻辑合取
x or y	逻辑析取
x == y	相等
x != y	不相等

Think of these operators as ways to make decisions in your code:

• not x - flip true/false values ​​to their opposites

  is_door_locked = True
  is_door_unlocked = not is_door_locked # Result: False

It's like saying "opposite" - if the door is locked, then being unlocked means it's open.

• x and y - both conditions must be true

  has_ticket = True
  has_id = True
  can_board_plane = has_ticket and has_id # Result: True

Just like you need a ticket and ID to board a plane, both values ​​must be true for the result to be true.

• x or y - at least one condition must be true.

  has_cash = False
  has_credit_card = True
  can_pay = has_cash or has_credit_card # Result: True

For example, when paying, you can use cash or credit card; you need one of these to be true.

• x == y - checks if two values ​​are the same

  password = "secret123"
  entry = "secret123"
  is_correct = password == entry # Result: True

It's like checking if two keys are the same.

• x != y - checks if two values ​​are different

  expected_price = 100
  actual_price = 90
  price_changed = expected_price != actual_price # Result: True

This is like checking to see if something is different, such as noticing that a price is different than expected. These operators help you make logical Boolean decisions.

Numbers - Integers and their variants

When using numbers in smart contracts, Vyper provides two basic methods for handling integers: signed integers and unsigned integers. Each method has its specific purpose, and understanding their differences is critical to writing efficient and safe code.

• Signed integer

Signed integers are probably the most versatile number type in Vyper, capable of representing both positive and negative values. Think of a bank account - you can make deposits (positive numbers) and withdraw money (negative numbers). This is where signed integers shine. When you declare a variable such as age: int8 = -5, you are telling Vyper to reserve 8 bits of space, which can hold any number between -128 and 127.

<code>is_active: bool = True
is_paused: bool = False

# 可以翻转布尔值
is_active = not is_active  # 现在是 False</code>

For larger values, Vyper provides larger storage capacity. The int256 type is typically used for a large number of numerical operations and can handle larger numbers. Consider tracking a company's profit and loss: balance: int256 = 1000. This can represent a large financial move in either direction.

• Unsigned integer

Some values ​​in the real world are never negative. You cannot have -3 apples or -5 users. This is where unsigned integers come into play. A statement like quantity: uint8 = 255 is perfect for inventory systems or user counting.

The uint8 type effectively uses 8 bits to store values ​​between 0 and 255, making it ideal for small positive numbers.

<code>is_active: bool = True
is_paused: bool = False

# 可以翻转布尔值
is_active = not is_active  # 现在是 False</code>

The most commonly used unsigned integer in Vyper is uint256. When you write price: uint256 = 1000 you create a variable that can hold a huge positive number, perfect for the number of tokens or the wei value in an Ethereum transaction.

• Decimal

When you need to use decimal points for precise calculations

<code># 有符号整数（可以为正数或负数）
age: int8 = -5          # 存储范围为 -128 到 127
balance: int256 = 1000  # 较大的范围用于更大的数字</code>

• Address - for Ethereum accounts

We use addresses every day to identify locations - your home, a store or a friend's home. In the Ethereum world, addresses work similarly, but instead of pointing to a physical location, they point to digital wallets and smart contracts. Let’s explore what makes these addresses unique and how they work in Vyper.

What is an Ethereum address?

<code># 无符号整数（只有正数）
quantity: uint8 = 255   # 存储范围为 0 到 255
price: uint256 = 1000   # 常用于存储大型正数</code>

Think of your Ethereum address as a unique digital mailbox. Just like your home address ensures that mail reaches only you, an Ethereum address ensures that cryptocurrencies and digital assets reach their intended destination. In Vyper we use a special type called address to handle these addresses.

When you write something like:

<code>price: decimal = 19.99  # 适用于财务计算
tax_rate: decimal = 0.15</code>

You are creating a variable that can only store valid Ethereum addresses. These addresses always start with "0x" followed by 40 characters consisting of numbers (0-9) and letters (a-f).

Real world examples Let's say you are building a simple digital wallet contract. You can store the address like this:

<code>owner: address = 0x123...  # 存储钱包地址
contract: address = 0xABC...</code>

Use address Addresses in Vyper have special properties. You can check the following:

• How many Ether coins does one address hold
• Whether an address belongs to a smart contract
• The code is stored in the contract address

For example, checking the balance of an address is as simple as this:

<code>owner: address = 0x71C7656EC7ab88b098defB751B7401B5f6d8976F</code>

Addresses help us navigate the blockchain, ensuring our digital assets and interactions reach their intended destination safely and reliably.

• byte array - for raw data

In Vyper, byte arrays are used to process raw binary data. Think of them as containers for storing information that a computer can directly process. Byte arrays are particularly useful when working with files, cryptographic hashes, or binary operations.

<code># 钱包的所有者
owner: address = 0x71C7656EC7ab88b098defB751B7401B5f6d8976F



# 可靠的备份地址
backup_wallet: address = 0x8626f6940E2eb28930eFb4CeF49B2d1F2C9C1199</code>

Static byte array Static byte arrays have a fixed size and cannot be changed. This makes it simple and efficient.

Example: Storing a fixed size hash Suppose you have a unique code such as a fingerprint that is always 32 bytes long. Here's how to store it in Vyper.

fixed_code: bytes32 This means bytes32 will always be 32 bytes.

Dynamic byte array

A dynamic byte array can accommodate data of different lengths if it does not exceed the maximum size. It helps in storing content like short messages.

Example: Save a short message Suppose you want to save a message, such as "Hello, World!", which can be up to 100 bytes long:

<code>is_active: bool = True
is_paused: bool = False

# 可以翻转布尔值
is_active = not is_active  # 现在是 False</code>

Okay, that’s it for today’s study. Our next article will examine more data types and understand their capabilities.

To read more of the above, check out the Vyper documentation and Vyper examples.

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