---初学者必背PY基础实例代码100例---
---初学者必背PY基础实例代码100例---
下面是关于Python数据类型、控制结构、函数、数据结构、类与继承的100个示例代码。这些示例将帮助你理解每个概念的基本用法和一些常见应用。
（一）数据类型示例（20例）
1. 整数和浮点数
```python
a = 10
b = 3.14
print(type(a), type(b))
```
2. 字符串
```python
s = "Hello, World!"
print(s)
```
3. 列表
```python
lst = [1, 2, 3, 4, 5]
print(lst)
```
4. 元组
```python
t = (10, 20, 30)
print(t)
```
5. 字典
```python
d = {'name': 'Alice', 'age': 25}
print(d)
```
6. 集合
```python
set1 = {1, 2, 3}
set2 = {3, 4, 5}
print(set1.union(set2))
```
7. 布尔值
```python
flag = True
print(flag)
```
8. None类型
```python
x = None
print(x)
```
9. 类型转换
```python
x = int(3.7)
y = str(123)
print(x, y)
```
10. 字符串格式化
```python
name = "Tom"
age = 30
print(f"My name is {name} and I am {age} years old.")
```
11. 列表切片
```python
lst = [0,1,2,3,4,5]
print(lst[2:5])
```
12. 字典获取值
```python
d = {'a': 1, 'b': 2}
print(d.get('a'))
```
13. 集合运算
```python
s1 = {1,2,3}
s2 = {3,4,5}
print(s1 & s2) # 交集
```
14. 复制列表
```python
lst1 = [1, 2]
lst2 = lst1.copy()
print(lst2)
```
15. 多类型列表
```python
mixed = [1, 'two', 3.0, True]
print(mixed)
```
16. 计算字符串长度
```python
s = "Python"
print(len(s))
```
17. 列表元素出现次数
```python
lst = [1,2,2,3,4,2]
print(lst.count(2))
```
18. 字典更新
```python
d = {'x': 1}
d.update({'y': 2})
print(d)
```
19. 集合添加元素
```python
s = {1,2}
s.add(3)
print(s)
```
20. 布尔值逻辑
```python
a = True and False
b = True or False
print(a, b)
```
（二）控制结构示例（20例）
21. if语句
```python
x = 10
if x > 5:
print("x大于5")
```
22. if-elif-else
```python
score = 85
if score >= 90:
print("A")
elif score >= 70:
print("B")
else:
print("C")
```
23. for循环
```python
for i in range(5):
print(i)
```
24. while循环
```python
count = 0
while count < 5:
print(count)
count += 1
```
25. 嵌套循环
```python
for i in range(3):
for j in range(2):
print(f"i={i}, j={j}")
```
26. 控制跳出（break）
```python
for i in range(10):
if i == 5:
break
print(i)
```
27. 控制继续（continue）
```python
for i in range(5):
if i == 2:
continue
print(i)
```
28. 使用pass占位
```python
if x > 0:
pass # 未来填充代码
```
29. 列表推导式
```python
squares = [x**2 for x in range(10)]
print(squares)
```
30. 字典推导式
```python
squared_dict = {x: x**2 for x in range(5)}
print(squared_dict)
```
31. 判断语句嵌套
```python
x = 10
if x > 5:
if x < 15:
print("x在5到15之间")
```
32. 三元表达式
```python
result = "偶数" if x % 2 == 0 else "奇数"
print(result)
```
33. 使用pass
```python
def future_feature():
pass
```
34. try-except异常处理
```python
try:
1 / 0
except ZeroDivisionError:
print("不能除以零！")
```
35. for循环遍历字典
```python
d = {'a': 1, 'b': 2}
for key, value in d.items():
print(key, value)
```
36. 逐行读取文件（示例）
```python
# with open('file.txt', 'r') as f:
# for line in f:
# print(line.strip())
```
37. 断言
```python
assert 2 + 2 == 4
```
38. 简单的条件表达式
```python
max_value = x if x > y else y
```
39. 定义函数
```python
def greet(name):
return f"Hello, {name}"
```
40. 使用递归
```python
def factorial(n):
return 1 if n == 0 else n * factorial(n - 1)
```
（三）函数示例（20例）
41. 无参数函数
```python
def hello():
print("Hello")
hello()
```
42. 有参数函数
```python
def add(a, b):
return a + b
print(add(3, 5))
```
43. 默认参数
```python
def power(base, exponent=2):
return base ** exponent
print(power(3))
```
44. 可变参数（*args）
```python
def sum_all(*args):
return sum(args)
print(sum_all(1, 2, 3))
```
45. 关键字参数（**kwargs）
```python
def print_info(**kwargs):
for key, value in kwargs.items():
print(f"{key}={value}")
print_info(name='Alice', age=30)
```
46. 嵌套函数
```python
def outer():
def inner():
print("Inner")
inner()
outer()
```
47. 返回多个值
```python
def get_point():
return (1, 2)
x, y = get_point()
```
48. 递归函数（阶乘）
```python
def factorial(n):
if n == 0:
return 1
else:
return n * factorial(n-1)
print(factorial(5))
```
49. 匿名函数（lambda）
```python
square = lambda x: x**2
print(square(4))
```
50. 高阶函数（map）
```python
nums = [1, 2, 3]
squares = list(map(lambda x: x**2, nums))
print(squares)
```
（四）数据结构示例（20例）
51. 使用列表
```python
numbers = [1, 2, 3]
numbers.append(4)
print(numbers)
```
52. 使用元组
```python
coordinates = (10.0, 20.0)
print(coordinates)
```
53. 使用字典
```python
person = {'name': 'Alice', 'age': 25}
person['city'] = 'New York'
print(person)
```
54. 使用集合去重
```python
s = [1, 2, 2, 3]
unique = set(s)
print(unique)
```
55. 使用列表作为堆栈
```python
stack = []
stack.append(1)
stack.append(2)
print(stack.pop())
```
56. 使用列表作为队列（deque）
```python
from collections import deque
queue = deque()
queue.append(1)
queue.append(2)
print(queue.popleft())
```
57. 嵌套列表
```python
matrix = [[1, 2], [3, 4]]
print(matrix[0][1])
```
58. 使用链表（自定义）
```python
class Node:
def __init__(self, data):
self.data = data
self.next = None
```
59. 栈的实现
```python
stack = []
stack.extend([1, 2, 3])
print(stack.pop())
```
60. 队列的实现
```python
from collections import deque
q = deque([1, 2, 3])
q.append(4)
print(q.popleft())
```
（五）class类与继承示例（20例）
61. 基础类定义
```python
class Person:
def __init__(self, name):
self.name = name
def greet(self):
print(f"Hello, my name is {self.name}")
```
62. 创建实例
```python
p = Person("Alice")
p.greet()
```
63. 类的继承
```python
class Student(Person):
def __init__(self, name, student_id):
super().__init__(name)
self.student_id = student_id
def study(self):
print(f"{self.name} is studying.")
```
64. 方法重写
```python
class Animal:
def speak(self):
print("Animal makes a sound")
class Dog(Animal):
def speak(self):
print("Woof!")
```
65. 多继承
```python
class Flyer:
def fly(self):
print("Flying")
class Bird(Animal, Flyer):
pass
```
66. 类变量和实例变量
```python
class Car:
wheels = 4
def __init__(self, color):
self.color = color
```
67. 静态方法
```python
class Math:
@staticmethod
def add(a, b):
return a + b
```
68. 类方法
```python
class Person:
count = 0
@classmethod
def get_count(cls):
return cls.count
```
69. 使用@property
```python
class Rectangle:
def __init__(self, width, height):
self._width = width
self._height = height
@property
def area(self):
return self._width * self._height
```
70. 抽象类（使用abc）
```python
from abc import ABC, abstractmethod
class Shape(ABC):
@abstractmethod
def area(self):
pass
```
71. 继承抽象类
```python
class Circle(Shape):
def __init__(self, radius):
self.radius = radius
def area(self):
import math
return math.pi * self.radius ** 2
```
72. 装饰器示例
```python
def decorator(func):
def wrapper():
print("Before function")
func()
print("After function")
return wrapper
@decorator
def say_hello():
print("Hello")
```
73. 类的私有变量
```python
class Example:
def __init__(self):
self.__private_var = 42
def get_private(self):
return self.__private_var
```
74. 类的继承多层结构
```python
class Animal:
pass
class Mammal(Animal):
pass
class Dog(Mammal):
pass
```
75. 方法链
```python
class Builder:
def __init__(self):
self.result = ""
def add(self, s):
self.result += s
return self
def build(self):
return self.result
b = Builder().add("Hello").add(" ").add("World").build()
print(b)
```
76. 继承构造函数调用
```python
class Parent:
def __init__(self):
print("Parent init")
class Child(Parent):
def __init__(self):
super().__init__()
print("Child init")
```
77. 使用__str__方法
```python
class Person:
def __init__(self, name):
self.name = name
def __str__(self):
return f"Person({self.name})"
```
78. 类变量修改
```python
class Counter:
count = 0
def increment(self):
Counter.count += 1
```
79. 动态添加方法（类型绑定）
```python
class MyClass:
pass
def new_method(self):
print("New method")
obj = MyClass()
import types
obj.new_method = types.MethodType(new_method, obj)
obj.new_method()
```
80. 单继承多重初始化调用
```python
class A:
def __init__(self):
print("A init")
class B(A):
def __init__(self):
super().__init__()
print("B init")
```
（六）其他实用示例（20例）
81. 测试所有字典值
```python
d = {'a': 1, 'b': 0}
if all(d.values()):
print('All true')
else:
print('Some false')
```
82. 生成器示例
```python
def countdown(n):
while n > 0:
yield n
n -= 1
for i in countdown(5):
print(i)
```
83. 简单的装饰器计时
```python
import time
def timer(func):
def wrapper():
start = time.time()
result = func()
end = time.time()
print(f"运行时间：{end - start}秒")
return result
return wrapper
```
84. 使用namedtuple
```python
from collections import namedtuple
Point = namedtuple('Point', ['x', 'y'])
p = Point(1, 2)
print(p.x, p.y)
```
85. 使用deque实现队列
```python
from collections import deque
queue = deque()
queue.append(1)
print(queue.popleft())
```
86. JSON处理
```python
import json
data = '{"name": "Alice", "age": 25}'
parsed = json.loads(data)
print(parsed['name'])
```
87. 解析日期
```python
from datetime import datetime
now = datetime.now()
print(now.strftime("%Y-%m-%d %H:%M:%S"))
```
88. 读取配置文件（ini）
```python
import configparser
config = configparser.ConfigParser()
# config.read('config.ini')
# print(config['section']['key'])
```
89. 使用异常捕获
```python
try:
result = 10 / 0
except ZeroDivisionError:
print("除零错误")
finally:
print("执行结束")
```
90. 复制对象（浅复制）
```python
import copy
lst1 = [1, 2]
lst2 = copy.copy(lst1)
```
91. 深复制
```python
deep_lst = copy.deepcopy(lst1)
```
92. 正则表达式
```python
import re
match = re.match(r'(\d+)', '123abc')
print(match.group(1))
```
93. 使用with打开文件
```python
with open('file.txt', 'w') as f:
f.write('Hello World')
```
94. 列表中的条件筛选
```python
evens = [x for x in range(10) if x % 2 == 0]
print(evens)
```
95. 计算平均值
```python
nums = [10, 20, 30]
avg = sum(nums) / len(nums)
print(avg)
```
96. 获取文件路径（os.path）
```python
import os
print(os.path.basename('/path/to/file.txt'))
```
97. 使用enumerate
```python
for index, value in enumerate(['a', 'b', 'c']):
print(index, value)
```
98. 线程示例（简单）
```python
import threading
def task():
print("Thread running")
thread = threading.Thread(target=task)
thread.start()
```
99. 定时执行（time.sleep）
```python
import time
print("Start")
time.sleep(2)
print("End after 2 seconds")
```
100. 简单类的__repr__方法
```python
class Person:
def __init__(self, name):
self.name = name
def __repr__(self):
return f"Person({self.name})"
```
以上示例涵盖了Python的基本数据类型、控制结构、函数定义与调用、常用数据结构、面向对象编程（类和继承）以及一些实用技巧。希望能帮助大家全面理解Python！