Today is the second day of leaning Python.

1.For Loop

   for i in range():
  print()

2.break and continue

   break : To jump out of this loop

   continue : To jump out of the current loop

3.list  []

   a = [1,2,3,4,5]     a[1:4]  Everying from the first to the fourth,but not the fourth.

                              a[1:]    from the first to the last

                              a[1: :2] This 2 represents the step size.(2,4) if it's -2  represents in the opposite direction

                              a.append('data')  a.insert(index,'data')

                              a.remove('data')  a.pop(index) If no input index ,it means that the last item is deleted.

                              a.count('data')     a.extend(b)  Add b to a     a.index('data')  Find index   

                              a.sort()   Sort lists from samll to large    a.reverse()   Reverse the contents of the list

4.tuple  ()

   a=(1,2,3,4,5)      Tuples are readable and unchangeable.

5.Format output

   print ("----%s----" % variable)

6.Determine whether the user input is a number?

    if variable.digit():   If it's number , return True  Else return False

7.dictionary

   dic={"name":"Mr","age":22,"sex":"man"}    Key-value pairs

   Key is Immutable  Changeless . It could be a string , a number or a tuple

   Value is Varibale . it could be a list , a string , a number

   The contents of the dictionary are disordered.  Access accordng to Key.

 

  

8.Shopping test  (source code)

    salary = input("请输入您的工资:")
    if salary.isdigit():
      salary = int(salary)
    shopping_car = []
    shop = [['iphone6', 6000],
        ['mac book', 80],
        ['coffee', 35],
        ['bicycle', 1500],
        ['computer', 4000, ]]
    while True:
      for i, v in enumerate(shop, 1):
      print(i, v)
      choose = input("请输入你要购买的物品编号(退出q):")
      if choose.isdigit():
        choose = int(choose)
        if choose>0 and choose<len(shop):
          p_item = shop[choose-1]
          if p_item[1] < salary:
            salary -= p_item[1]
            shopping_car.append(p_item)
          else:
            print("余额不足,还剩%s元钱" % salary)
            print(p_item)
        else:
          print("商品编码不存在")
      elif choose == 'q':
        print("---------购买的商品--------")
        for i in shopping_car:
          print(i)
          print("您还剩%s元钱" % salary)
          break
      else:
      print("金钱不足")