1. Let the user enter any string, get the string and calculate how many digits there are.

total = 0
text = input("Please enter the content")
a = 0
while a <len(text):
        if text[a].isdigit():
               total += 1
        a += 1
print(total)

2. Implementing an integer addition calculator (adding two numbers): (strings and lists)

Train of thought:
content = input('Please input:') # [5+9]  or [5 +9]  perhaps [ 5 + 9 ]
result = content.split('+')
# print(result) # ['55 ', ' 99 ']
v1 = int(result[0]) # "55"
v2 = int(result[1]) # " 99 "
v3 = v1 + v2
print(v3)

Train of thought two:

  content = input('Please input:')   # [5+9] or [5 +9] perhaps [ 5 + 9 ]
  content = content.strip()    # [5+9] or [5+9] or [5+9]
  v1 = int(content[0])
  v2 = int(content[-1])
  v3 = v1 + v2

  print(v3)

3. Enter user and password and check (list)

users = []
for i in range(0,3)
       name = input("Please enter a username and password")
       users.append(name)
print(users)      #Enter user and password     ['alex,123', 'oldboy,888', 'lishaoqi,123']
users_name = input("enter one user name")
password = input('Please input a password')         #User and password verification
for items in users:
        result = items.split(",")
        use = result[0]
        pwd = result[1]
        if user == username and pwd == password:
               print('Login successfully')
               break

4. Please implement it in code: (dictionary)

　　　message = "k1|v1,k2|v2,k3|123......." # ,k3|123
　　　info = {'k1':'v1','k2':'v2','k3':'123'}

info = {}
message = "k1|v1,k2|v2,k3|123"
for item in message.split(','): # ["k1|v1","k2|v2","k3|123"]
    v1,v2 = item.split('|')
    info[v1] = v2
print(info)

5. Create a user list, and then let the user enter a username and password for login. When entering N, no more input (list plus dictionary)

user_list = [
{'user':'alex','pwd':'123'},
{'user':'oldboy','pwd':'123'},
{'user':'lishaoqi','pwd':'1123'},
{'user':'liqihang','pwd':'123'},
{'user':'xxx','pwd':'123'}, # N
]

user_list = []
while True:
    con = input('enter one user name')
    if con == "N":
        break
    p = input('Please input a password')
    info = {}
    info['user'] = con
    info['pwd'] = p
    user_list.append(info)
print(user_list)       #Building User Lists
name= input('enter one user name')
pwd = input('Please input a password')
result = 'Login failure'
for i in user_list:
    if i['user'] == name and i['pwd'] == pwd:
        result = 'Login successfully'
        break
print(result)

6. Output commodity list, user input serial number, display the selected commodity

 List of goods:
   goods = [
     {"name": "computer", "price": 1999},
     {"name": "mouse", "price": 10},
     {"name": "yacht", "price": 20},
     {"name": "beauty", "price": 998}
  ]
 Requirement:
 1: The page shows serial number + commodity name + commodity price, such as:
       1 Computer 1999
       2 mouse 10
    ...
 2: The user enters the serial number of the selected commodity, and then prints the name and price of the commodity.
 3: If the serial number of the goods entered by the user is incorrect, the user will be prompted for incorrect input and re-input.
 4: The user enters Q or Q and exits the program.

 goods = [
         {"name": "Computer", "price": 1999},
         {"name": "mouse", "price": 10},
        {"name": "Yacht", "price": 20},
         {"name": "Beauty", "price": 998}
     ]
 a = 1
 for i in goods:
     print(a,i)
     a += 1
 while True:
     content = input('Please choose the serial number of the goods.:')
     if content.upper() == 'Q':
         break
     elif int(content) >len(goods) or int(content) <1:
         print('Incorrect input,Please re-enter')
         continue
     else:
         print(goods[int(content)-1]['name'],goods[int(content)-1]['price'])