This section provides a summary knowledge:
- Entry
- Note
- cycle
- String formatting
- Operators
- coding
In this section:
1. Enter
user_name = input("请输入你的姓名:")
message = user_name + "进入"
print(message)note:
- After the input is always the input string to get content
- py version differences:
- py2: name = raw_input ( 'Enter')
- py3: name = input ( 'Enter')
user_name = input("请输入你的姓名:")
password = input("请输入你的密码:")
#用户名和密码拼接
content = "你的用户名是：" + user_name + "；你的密码是：" + passwod
#输出用户名和密码拼接的结果
print(content)2. Comment
# 单行注释
"""
多行注释
"""3. Cycle
3.1 if..else
Primary conditional statement:
gender = input("请输入性别：")
"""
如果是男生：打印再见
否则：打印来呀
"""
if gender == "男"
print("再见")
else:
print("来呀")2.elif conditions
gender = input("请输入性别：")
"""
如果是男生：打印再见
如果是女生：打印来呀
如果是人妖：打印找别人去
否则：打印滚
最后加end
"""
if gender == "男"
print("再见")
elif gender == "女"
print("来呀")
elif gender == "人妖"
print("找别人去")
else:
print("滚")
print("end")3. Exercises
#让用户输入一个数字，猜：如果数字 > 50,则输出：大了；如果数字 <= 50,则输出：小了。
num = input("请输入一个数字：")
number = int(num)
if number > 50:
print("大了")
else:
print("小了")
#用户名密码登录
username = input('请输入用户名：')
password = input('请输入密码：')
if username == "alex" and password == "123":
print("欢迎")
else :
print("用户名密码或错误")note:
- After the input is a string, the string can not be compared, pay attention to the type of conversion
3.2 if nested
message = """欢迎致电10086
1.话费查询；
2.流量服务；
3.业务办理；
4.人工服务"""
print(message)
index = input("请选择业务类型：")
index = int(index)
if index == 1:
print("话费查询")
elif index == 2:
print("流量服务")
elif index == 3:
content = """业务办理
1.修改密码
2.修改套餐
3.停机
"""
print(content)
value = input("请选择所需的业务办理类型")
value = int(value)
if value == 1:
print("修改密码")
elif value == 2:
print("修改套餐")
elif value == 3:
print("停机")
else:
print("输入错误")
elif index == 4:
print("人工服务")
else:
print("输入错误")3.3 while loop:
After 3.3.1 while adding conditions
count = 1
while True:
print(count)
count = count + 1 #结果为count每次加1，无限循环while True:
count = 1
print(count)
count = count + 1 #结果为1，无限循环count = 1
while count <= 10:
print(count)
count = count + 1 #结果为1-10Exercise: Print 10, no 7
count = 1
while count <= 10:
if count != 7:
print(count)
count = count + 1 #方法一：使用不等于!=
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~·
count = 1
while count <= 10:
if count == 7:
pass
else:
print(count)
count = count + 1 #方法二：使用不等于pass3.3.2 Keywords: break
Note: break to end while the entire cycle
3.3.3 Keyword: continue
Note: continue to re-start this cycle
3.3.4 loop while else (not used)
count = 1
while count <= 10:
print(count)
count = count + 1
else: #不在满足while循环条件后触发，或条件等于False
print("else语句")
print("结束")
#结果：打印1-10 else语句 结束3.3.5 while summary:
- body of the while (+ after determination condition)
- break ends the while loop
- continue the end of this cycle, the cycle begins again
- while else loop condition is not met after the trigger, or condition equal to False
2. string formatting:
% S is a placeholder, parameters separated by commas
name = input("请输入你的名字：")
do = input("在干什么：")
template = "%s在教室，%s."%(name,do)
print(template)name = 'alex'
template = "%s现在手机的电量是100%%"%(name) #参数内如果有%，使用两个%%可以不进行占位符
print(template)Knowledge points:
- % S placeholder, the placeholder may represent all
- % D placeholder numeric placeholder
- %% placeholder canceled, the output is a%
name = input("请输入姓名:")
age = input("请输入年龄：")
age = int(age)
job = input("请输入工作：")
hobby = input("请输入爱好：")
msg = '''
------------info------------
Name : %s
age : %d
job : %s
hobby : %s
------------end-------------
'''
data = msg %(name,age,job,hobby)
print(data)3. Operator
+ Plus - minus * multiplication, / division sign,% remainder, a power of ** // rounded
###打印1-100内的奇数
count = 1
while count <= 100:
val = count % 2
if val == 1:
print(count)
count=count + 1 #方法1
###################
count = 1
while count <= 100:
if count % 2 == 1:
print(count)
count=count + 1 #方法2###练习题，1-100以内所有数字相加
total = 0
count = 1
while count <= 100:
total = total + count
count=count + 1
print(total)Conversion:
- String (str) to Digital (int)
- Digital (int) transfected string (str)
- Null string ( "") and digital (0) after the turn Boolean is False, True all remaining
or * Note: value will first determine whether True, the output value of True
value = 1 or 9
print(value) #会先判断1和9是否为True，1为True，9就不做判断，输出结果为1
value = 0 or 9
print(value) #会先判断0和9是否为True，0为False，再判断9为True，输出结果为9
value = 0 or ""
print(value) #0和“”都为False，输出结果为空，输出最后一个结果and * Note: first determine whether to False, output False, if all is True, the last output value
v1 = 1 and 9 #会先判断1，为True，再判断9，为True。输出9
v2 = 1 and 0 #会先判断1，为True，再判断0，为False。输出0
v3 = 0 and 7 #会先判断0，为False，输出0
v4 = 0 and "" #会先判断0，为False，输出0
v5 = 1 and 7 and "" #会先判断1和7，输出7，再判断7和“”，输出空值Comprehensive:
v6 = 1 and 9 or 0 and 6 #会先判断and，1 and 9，结果是9；再判断0 and 6，结果为0，再判断9 or 0，输出9A logical operation: in the absence () is, not higher than the priority and, above or, as the relationship ()> not> and> or, the same priority is calculated from left to right
4. encoding
- Coding extension
- ascii
- Unicode
- ecs2 beginning out with
- ecs4 later began to use
- utf-8, Chinese three bytes, (for global use) must be encoded using the utf-8
- utf-16
- gbk, Chinese use two bytes (Asia use)
- gb2312, Chinese use two bytes (Asia use) gbk extension
Coding units:
String: "China" "hello"
Character: "in the" "e"
Byte: encoding unicode (a character of 4 bytes), encoding utf-8 (3 bytes for the Chinese words, the English alphabet is a single byte)
Place: 01010101
Unit conversion:
- 8bit（位）=1byte（字节） - 1024byte（字节）=1KB - 1024GB=1TB - 1024TB=1PB - 1024PB=1EB
ASCII code to add
Coding usage scenarios:
- Data calculation computer memory, data length will match the sum will be used unicode.
- Byte using a relatively small data transmission coding, e.g. utf-8