python之旅--基础

 1 #格式化输出
 2 name = input("name:")
 3 age = input("age")
 4 #age = int(input("age")) 转换数据类型 整型 integer
 5 print(type(age)) #打印数据类型
 6 job = input("job:")
 7 
 8 #格式化输出1 拼接 开启内存多
 9 info1 = ‘‘‘
10     ---output one---
11     name: ‘‘‘+name+ ‘‘‘
12     age: ‘‘‘+age+‘‘‘
13     job: ‘‘‘+job+‘‘‘
14 ‘‘‘
15 print(info1)
16 
17 #格式化输出2
18 #%s字符 %d 小数 %d浮点数
19 info2 = ‘‘‘
20     ---output two---
21     name: %s
22     age: %s
23     job: %s
24 ‘‘‘ %(name,age,job)
25 print(info2)
26 
27 #格式化输出3
28 info3 = ‘‘‘
29     ---output three---
30     name: {Name}
31     age: {Age}
32     job: {Job}
33 ‘‘‘.format(Name=name,
34            Age=age,
35            Job=job)
36 print(info3)
37 
38 #格式化输出4
39 info4 = ‘‘‘
40     ---output four---
41     name: {0}
42     age: {1}
43     job: {2}
44 ‘‘‘.format(name,age,job)
45 print(info4)

#if else 语句
user_name = "test"
pass_word = "123"

username = input("username:")
password = input("password:")

if username == user_name and password == pass_word:
    print("Welcome user {name} login...".format(name=username))
else:
    print("Invalid username/password!")

count = 0
while True:
    print(count)
    count += 1
    if count == 100:
        break

#for循环 跳着打印
for i in range(0,10,2):
    print("loop ",i)

#break结束当次循环
for i in range(10):
    print("===",i)
    for j in range(10):
        print(j)
        if j > 5:
            break #跳出当次循环

continue
#continue 跳出本次循环开始下次循环
for i in range(10):
    if i<5:
        continue #不往下走了,直接进入下一次loop 
    print("loop:", i )

break
for i in range(10):
    if i>5:
        break #不往下走了,直接跳出整个loop
    print("loop:", i )

 1 #if elif else 语句 while True
 2 age = 30
 3 count = 0
 4 while True:
 5     guess_age = int(input("guess age:"))
 6     if guess_age == age:
 7         print("right...")
 8         break
 9     elif guess_age > age:
10         print("smaller...")
11     else:
12         print("bigger...")
13     if count == 3:
14         break
15     count += 1
16 
17 #while 后面直接加条件 else
18 age = 30
19 count = 0
20 while count < 3:
21     guess_age = int(input("guess age:"))
22     if guess_age == age:
23         print("right...")
24         break
25     elif guess_age > age:
26         print("smaller...")
27     else:
28         print("bigger...")
29     count += 1
30 else:
31     print("too many times")
32 # if count == 3:
33 #     print("too many times")
34 
35 #改为for循环
36 age = 30
37 for i  in range(3):
38     guess_age = int(input("guess age:"))
39     if guess_age == age:
40         print("right...")
41         break
42     elif guess_age > age:
43         print("smaller...")
44     else:
45         print("bigger...")
46 else:
47     print("too many times")
48 
49 #每执行三次 询问一次
50 age = 30
51 count = 0
52 while count < 3:
53     guess_age = int(input("guess age:"))
54     if guess_age == age:
55         print("right...")
56         break
57     elif guess_age > age:
58         print("smaller...")
59     else:
60         print("bigger...")
61     count += 1
62     if count == 3:
63         countine_con = input("keep input")
64         if countine_con != ‘n‘:
65             count = 0

>>> a,b,c = 1,3,5
>>> d = a if a > b else c

#不用三元运算
>>> if a > b:d = a
... else:d=c
...

#bytes --> string 用decode 编码
#string --> bytes 用incode 解码
#string(字符类型) --> bytes（二进制类型）
>>> msg = "欢迎"
>>> print(msg.encode(encoding="utf-8")) #写上字符编码
b‘\xe6\xac\xa2\xe8\xbf\x8e‘
>>> print(msg.encode()) #系统默认字符编码为utf-8
b‘\xe6\xac\xa2\xe8\xbf\x8e‘

#bytes --> string
>>> print(msg.encode(encoding="utf-8").decode(encoding="utf-8"))
欢迎