Python是一門高級、通用用途、多范式、動態類型、解釋型程序設計語言。

Hello World

def sayHello:
    print("Hello World!")

if __name__ == "__main__":
    sayHello()

python helloworld.py

Dynamical typing

多范式

Procedural

過程式編程的核心概念是：數據結構和過程。Python中，數據結構由類實現，過程由函數實現。

使用Class定義結構

>>> class Node:
...     def __init__(self):
...         self.value = None
...         self.previous = None
...         self.next = None
...

>>> head = Node()
>>> head.value=0
>>> second = Node()
>>> second.value=1
>>> head.next = second
>>> second.previous = head
>>> head.value
0
>>> head.next.value
1

使用函數實現過程

>>> def fibo(n):
...     if n == 0:
...         return 1
...     if n == 1:
...         return 1
...     return fibo(n-1) + fibo(n-2)
...

>>> fibo(10)
89

Object-Oriented

Objecte Oriented 的核心元素是Class和Object。Object Oriented的四大特性是：

Class和Object

聲明Class

class ClassName(BaseClassName):
    def __init__(self):
        self.name = "default"
    def otherMethod(self, parameters):
        # do something

Class使用關鍵字class聲明。
基類可選，默認為object。
構造器固定名字為__init__。
字段在構造器中顯示聲明。
方法的第一個參數必需是self - object自身。

創建Object

aObject = ClassName()

Encapsulation 封裝

Public Access

Protected Access

Private Access

class Person:
    def __init__(self, name):
        self.__name = name
    def sayHello(self):
        print("Hello "+self.__name)
    def rename(self, newName):
        self.__name = newName

>>> a = Person("Bob")
>>> a.__name
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Person' object has no attribute '__name'
>>> a.sayHello()
Hello Bob
>>> a.rename("Mike")
>>> a.sayHello()
Hello Mike

Inheritence 繼承

Abstraction 抽象

Polymorphysm 多態

Functional

Function as First-Class

Immutable Collection

內建類和函數

List

創建空List

>>> a = []
>>> a
[]
>>>

創建帶元素的List

>>> a = [1,2,3]
>>> a
[1, 2, 3]
>>>

往List添加元素

>>> a = [1,2,3]
>>> a
[1, 2, 3]
>>> a.append(4)
>>> a
[1, 2, 3, 4]
>>>

往List指定位置插入元素

>>> a = [1,2,3]
>>> a
[1, 2, 3]
>>> a.insert(1,10)
>>> a
[1, 10, 2, 3]
>>>

從list中移除元素

>>> a = [1,2,3]
>>> a
[1, 2, 3]
>>> a.remove(2)
>>> a
[1, 3]
>>>

從List中移除指定位置上的元素

>>> a = [1,2,3]
>>> a
[1, 2, 3]
>>> del a[1]
>>> a
[1, 3]
>>>

获取List中指定位置的元素

>>> a = [1,2,3]
>>> a
[1, 2, 3]
>>> a[1]
2
>>>

获取List的子串

>>> a = [1,2,3,4]
>>> a
[1, 2, 3, 4]
>>> a[1:3]
[2, 3]
>>>

壓棧

>>> a = [1,2,3]
>>> a
[1, 2, 3]
>>> a.append(4)
>>> a
[1, 2, 3, 4]
>>>

出棧

>>> a = [1,2,3,4]
>>> a
[1, 2, 3, 4]
>>> a.pop()
4
>>>

Tuple

創建空Tuple

>>> a = ()
>>> a
()
>>>

創建有值的Tuple

>>> a = (1,2,3)
>>> a
(1, 2, 3)
>>>

通過下標訪問Tuple內元素

>>> a = (1,2,3)
>>> a
(1, 2, 3)
>>> a[1]
2
>>>

自動解包Tuple

>>> a = (1,2,3)
>>> a
(1, 2, 3)
>>> one, two, three = a
>>> one
1
>>> two
2
>>> three
3
>>>

Set

創建空Set

>>> s = {}
>>> s
{}
>>>

創建包含元素的Set

>>> s = {1,2,3}
>>> s
{1, 2, 3}

往Set中添加元素

>>> s = {1,2,3}
>>> s
{1, 2, 3}
>>> s.add(4)
>>> s
{1, 2, 3, 4}

從Set中移除元素

>>> s = {1,2,3}
>>> s
{1, 2, 3}
>>> s.remove(2)
>>> s
{1, 3}

一個小時學會Python

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