python学习第一天

Posted 2020-09-27

一、python第一行代码：

1 name = "你好，世界"
2 print(name)

二、变量：

1 name = "SunDM12"
2 name2 = name
3 print("my name : ",name, name2)
4 
5 name = "wangba"
6 print(name, name2)

name前后变化，而name2 = name已经将“SunDM12”赋值给了name2，name变化后，name2不再变化

三、交互：

1 username = input("username ： ")
2 print(username)

input函数：用户可以在界面上显示输入字符，并赋值给了username

 1 name = input("name :")
 2 age = input("age :")
 3 job = input("job :")
 4 salary = input("salary :")
 5 
 6 info = ‘‘‘
 7 ------ info of %s ------
 8 name : %s
 9 age : %s
10 job : %s
11 salary : %s
12 ‘‘‘%(name, name, age, job, salary)

在屏幕打印的第一种格式。

%s是字符串；%d是双精度；%f是浮点型

1 info2 = ‘‘‘
2 ------- info of {_name} -------
3 name : {_name}
4 age : {_age}
5 job : {_job}
6 salary : {_salary}
7 ‘‘‘.format(_name=name,
8                _name=name,_age=age,_job=job,_salary=salary)        

在屏幕打印的第二种格式。

1 info3 = ‘‘‘
2 ------ info of {0} ------
3 name : {0}
4 age : {1}
5 job : {2}
6 salary : {3}
7 ‘‘‘.format(name,age,job,salary)

在屏幕打印的第三种格式。

四、登陆密码：

 1 import getpass
 2 
 3 _username = ‘SunDM12‘
 4 _password = ‘123456‘
 5 
 6 username = input(‘username :‘)
 7 password = input(‘password :‘)
 8 print(username,password)
 9 
10 if _username == username and _password == password
11     print("welcome user {name} login...".format(name = username))
12 else:
13     print("Invalid username or password!")

其中getpass是一个package，提供可移植的面膜输入

1. getpass.getpass()

2. getpass.getuser()

五、猜密码游戏

1 correct_number = 12
2 guess_number = int(input("guess number:"))
3 
4 if correct_number == guess_number:
5     print("yes,you got it...")
6 elif guess_number >correct_number:
7     print("think smaller...")
8 else:
9     print("think bigeer...")

其中input函数输入是一个字符，此时要将其强制转换为整型

5.1 while循环

1 count = 0
2 while True:
3     print("count :",count)
4     count = count +1
5     if count == 1000:
6         break

其中break表示跳出整个循环

correct_number = 12
count = 0

while count<3:
    guess_number = int(input("guess number:"))
    if correct_number == guess_number:
        print("yes,you got it...")
    elif guess_number >correct_number:
        print("think smaller...")
    else:
        print("think bigeer...")
    count + = 1

else:
    print("you have tried too many times.")

利用while循环进行设计猜数字游戏

5.2 for循环

1 for i in range(10):
2     print("loop ",i)

显示1到10

1 for i in range(0,10,2):
2     print("loop :",i)

2是步长

correct_number = 12

for i in range(3):
    guess_number = int(input("guess number:"))
    if correct_number == guess_number:
        print("yes,you got it...")
    elif guess_number >correct_number:
        print("think smaller...")
    else:
        print("think bigeer...")

else:
    print("you have tried too many times.")

利用for循环进行猜数字游戏

5.3 continue和break的区别

 1 for i in range(10):
 2     if i<5:
 3         print("loop",i)
 4     else:
 5         continue
 6     print("....")
 7 
 8 for i in range(10):
 9     print(‘-------‘,i)
10     for j in range(10):
11         print(j)
12         if j>5:
13             break

continue忽略当前语句，继续执行下一行

break跳出当前执行的整个循环