新手學python之新體驗

1. 使用縮進方式做為程式塊開始結束的標示，程式換行在行末尾加 ""

2. 元祖(Tuple)數據類型，和List的不同是Tuple不能修改，優點是執行速度比List快，因為不能修改也就比較安全，團隊開發某些情況會用到。

3. Dict字典類型，若鍵有重複時，後面的建值會覆蓋掉前面的。

dict = {"banana": 20, "apple": 30, "orange": 40, "banana": 30}
print(dict["banana"])  #30 

   字典類型的排列順序是隨機的，與設定的順序不一定相同，所以在讀取時就不能使用index。

dict = {"banana":20, "apple": 30}
result = dict.items()  # 取得以[鍵:值]為組合的Array
                               # [("banana":20), ("apple":30)]
result = dict.setdefault("apple", 50)  # 30
result = dict.setdefault("orange", 80)  # create new

fruits = ["apple", "mango", "orange"] #list
numbers = (1, 2, 3) #tuple
alphabets = {'a':'apple', 'b':'ball', 'c':'cat'} #dictionary
vowels = {'a', 'e', 'i' , 'o', 'u'} #set

4. python3 內建了SQLite, 非常方便储存數據，不需要再額外設定database環境

5. pyhon class 的 structure function.

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age

  def myfunc(self):
    print("Hello my name is " + self.name)

p1 = Person("John", 36)
p1.myfunc()

# the function called __init__(), which is always executed when the class is being initiated.

# Use the __init__() function to assign values to object properties, or other operations that are necessary to do when the object is being created

# The self parameter is a reference to the current instance of the class, and is used to access variables that belongs to the class.

# It does not have to be named self , you can call it whatever you like, but it has to be the first parameter of any function in the class

 6. string join

sentence = ['this','is','a','sentence']
'-'.join(sentence)
# this-is-a-sentence

7. function as function argument

def Calculate(func, *args):
    print(func(*args))
    
def Add(arg1, arg2):
    return arg1 + arg2

def Sub(arg1, arg2):
    return arg1 - arg2

Calculate(Add, 1, 3)  # 4
Calculate(Sub, 1, 3)  # -1

另外還有一種 keyword argument的用法，Calulate(func, **keywordArgs)