代码示例
代码示例
这个页面展示了不同编程语言的代码示例，用于测试代码块的样式。
HTML 示例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>HTML Example</title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<header>
<h1>Welcome to My Website</h1>
<nav>
<ul>
<li><a href="/">Home</a></li>
<li><a href="/about">About</a></li>
<li><a href="/contact">Contact</a></li>
</ul>
</nav>
</header>
<main>
<section>
<h2>About Us</h2>
<p>This is a paragraph about our company.</p>
</section>
</main>
<footer>
<p>© 2023 My Company</p>
</footer>
</body>
</html>
CSS 示例
/* Basic reset */
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
body {
font-family: Arial, sans-serif;
line-height: 1.6;
color: #333;
background-color: #f4f4f4;
}
header {
background-color: #35424a;
color: white;
padding: 20px;
border-bottom: 3px solid #e8491d;
}
nav ul {
display: flex;
list-style: none;
}
nav ul li {
margin-right: 20px;
}
nav a {
color: white;
text-decoration: none;
}
main {
padding: 30px;
max-width: 1200px;
margin: 0 auto;
}
section {
margin-bottom: 30px;
}
h1, h2 {
margin-bottom: 15px;
}
footer {
background-color: #35424a;
color: white;
text-align: center;
padding: 20px;
margin-top: 40px;
}
JavaScript 示例
// Example of a class in JavaScript
class Person {
constructor(name, age) {
this.name = name;
this.age = age;
}
greet() {
console.log(`Hello, my name is ${this.name} and I am ${this.age} years old.`);
}
static compareAges(person1, person2) {
if (person1.age > person2.age) {
return `${person1.name} is older than ${person2.name}`;
} else if (person1.age < person2.age) {
return `${person1.name} is younger than ${person2.name}`;
} else {
return `${person1.name} and ${person2.name} are the same age`;
}
}
}
// Creating instances
const john = new Person('John', 30);
const jane = new Person('Jane', 25);
// Using methods
john.greet(); // Output: Hello, my name is John and I am 30 years old.
jane.greet(); // Output: Hello, my name is Jane and I am 25 years old.
// Using static method
console.log(Person.compareAges(john, jane)); // Output: John is older than Jane
// Example of async/await
async function fetchUserData(userId) {
try {
const response = await fetch(`https://api.example.com/users/${userId}`);
if (!response.ok) {
throw new Error(`HTTP error! Status: ${response.status}`);
}
const data = await response.json();
return data;
} catch (error) {
console.error('Error fetching user data:', error);
return null;
}
}
// Using the async function
fetchUserData(123)
.then(user => {
if (user) {
console.log('User data:', user);
} else {
console.log('Failed to fetch user data');
}
});
Python 示例
# Example of a class in Python
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
def greet(self):
print(f"Hello, my name is {self.name} and I am {self.age} years old.")
@staticmethod
def compare_ages(person1, person2):
if person1.age > person2.age:
return f"{person1.name} is older than {person2.name}"
elif person1.age < person2.age:
return f"{person1.name} is younger than {person2.name}"
else:
return f"{person1.name} and {person2.name} are the same age"
# Creating instances
john = Person("John", 30)
jane = Person("Jane", 25)
# Using methods
john.greet() # Output: Hello, my name is John and I am 30 years old.
jane.greet() # Output: Hello, my name is Jane and I am 25 years old.
# Using static method
print(Person.compare_ages(john, jane)) # Output: John is older than Jane
# Example of async function in Python (using asyncio)
import asyncio
import aiohttp
async def fetch_user_data(user_id):
try:
async with aiohttp.ClientSession() as session:
async with session.get(f"https://api.example.com/users/{user_id}") as response:
if response.status != 200:
raise Exception(f"HTTP error! Status: {response.status}")
data = await response.json()
return data
except Exception as e:
print(f"Error fetching user data: {e}")
return None
# Using the async function
async def main():
user = await fetch_user_data(123)
if user:
print("User data:", user)
else:
print("Failed to fetch user data")
# Run the async function
if __name__ == "__main__":
asyncio.run(main())
Go 示例
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"strconv"
)
// Person struct
type Person struct {
Name string `json:"name"`
Age int `json:"age"`
}
// Greet method for Person
func (p *Person) Greet() {
fmt.Printf("Hello, my name is %s and I am %d years old.\n", p.Name, p.Age)
}
// CompareAges static function
func CompareAges(person1, person2 *Person) string {
if person1.Age > person2.Age {
return fmt.Sprintf("%s is older than %s", person1.Name, person2.Name)
} else if person1.Age < person2.Age {
return fmt.Sprintf("%s is younger than %s", person1.Name, person2.Name)
} else {
return fmt.Sprintf("%s and %s are the same age", person1.Name, person2.Name)
}
}
// FetchUserData function
func FetchUserData(userID int) (*Person, error) {
url := fmt.Sprintf("https://api.example.com/users/%d", userID)
resp, err := http.Get(url)
if err != nil {
return nil, err
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return nil, fmt.Errorf("HTTP error! Status: %d", resp.StatusCode)
}
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return nil, err
}
var person Person
err = json.Unmarshal(body, &person)
if err != nil {
return nil, err
}
return &person, nil
}
func main() {
// Creating instances
john := &Person{Name: "John", Age: 30}
jane := &Person{Name: "Jane", Age: 25}
// Using methods
john.Greet() // Output: Hello, my name is John and I am 30 years old.
jane.Greet() // Output: Hello, my name is Jane and I am 25 years old.
// Using static function
fmt.Println(CompareAges(john, jane)) // Output: John is older than Jane
// Using FetchUserData
userID := 123
user, err := FetchUserData(userID)
if err != nil {
fmt.Printf("Error fetching user data: %v\n", err)
} else {
fmt.Printf("User data: %+v\n", user)
}
}
SQL 示例
-- Create a users table
CREATE TABLE users (
id SERIAL PRIMARY KEY,
name VARCHAR(100) NOT NULL,
email VARCHAR(100) UNIQUE NOT NULL,
age INT CHECK (age >= 0),
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);
-- Insert some users
INSERT INTO users (name, email, age) VALUES
('John Doe', 'john@example.com', 30),
('Jane Smith', 'jane@example.com', 25),
('Bob Johnson', 'bob@example.com', 35);
-- Select all users
SELECT * FROM users;
-- Select users with age greater than 30
SELECT name, email, age
FROM users
WHERE age > 30;
-- Update a user's email
UPDATE users
SET email = 'john.doe@example.com'
WHERE id = 1;
-- Join users with their orders
SELECT u.name, o.order_id, o.total_amount
FROM users u
JOIN orders o ON u.id = o.user_id
WHERE o.order_date > '2023-01-01'
ORDER BY o.order_date DESC;
-- Create a view for active users
CREATE VIEW active_users AS
SELECT id, name, email
FROM users
WHERE last_login_date > CURRENT_DATE - INTERVAL '30 days';
-- Create a stored procedure
CREATE PROCEDURE update_user_age(user_id INT, new_age INT)
LANGUAGE plpgsql
AS $$
BEGIN
UPDATE users SET age = new_age WHERE id = user_id;
COMMIT;
END;
$$;
-- Call the stored procedure
CALL update_user_age(1, 31);
JSON 示例
{
"users": [
{
"id": 1,
"name": "John Doe",
"email": "john@example.com",
"age": 30,
"address": {
"street": "123 Main St",
"city": "New York",
"state": "NY",
"zipCode": "10001"
},
"phoneNumbers": [
{
"type": "home",
"number": "212-555-1234"
},
{
"type": "work",
"number": "646-555-5678"
}
],
"isActive": true,
"roles": ["user", "admin"]
},
{
"id": 2,
"name": "Jane Smith",
"email": "jane@example.com",
"age": 25,
"address": {
"street": "456 Park Ave",
"city": "Boston",
"state": "MA",
"zipCode": "02101"
},
"phoneNumbers": [
{
"type": "mobile",
"number": "617-555-9876"
}
],
"isActive": true,
"roles": ["user"]
}
],
"metadata": {
"totalCount": 2,
"lastUpdated": "2023-03-15T12:00:00Z",
"version": "1.0.0"
},
"settings": {
"theme": "dark",
"notifications": {
"email": true,
"push": false
},
"language": "en-US"
}
}