pythonday02基础与运算符

今日概要

1.循环

2.字符串格式化

3.运算符

4.编码


if的嵌套

score = input('请输入成绩')
score_int = int(score)
if score_int >= 90:
    print('A')
elif score_int >=80:
    print('B')
elif score_int >=70:
    print('C')
else:
    print('D')

10086示例

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('请输入你要选择的服务:')
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. 更改套餐;
    3. 停机;"""
    print(content)
    value = input('请输入要办理的业务:')
    value = int(value)
    if value == 1:
        print('修改密码')
    elif value == 2:
        print('更改套餐')
    elif value == 3:
        print('停机')
    else:
        print('错误')
elif index == 4:
    print('人工服务')
else:
    print('输入错误')

循环语句

# 1. 循环打印 “人生苦短,我用Python。”
"""
while True:
    print('人生苦短,我用Python。')
"""

# 2. while后加入条件
"""
while 1>0 and 2>1:
    print('人生苦短,我用Python。')
"""

# 3. 数字相加
"""
count = 1
value = count + 1
print(value)
"""
"""
count = 1
count = count + 1
print(count)
"""
# 4. 请通过循环,让count每次循环都 + 1 .
"""
count = 1
while True:
    print(count)
    count = count + 1
"""
# 练习
"""
while True:
    count = 1
    print(count)
    count = count + 1
"""

# 5. 请通过循环,1 2 3 .. 10.
"""
count = 1
while count <= 10:
    print(count)
    count = count + 1
print('结束')
"""
# 6. 请通过循环,1 2 3 4 5 6    8 9 10.  # 快速注释 ctrl+?
"""
# 错误示例
count = 1
while count <= 10 and count != 7 :
    print(count)
    count = count + 1
"""

"""
# 正确
count = 1
while count <= 6:
    print(count)
    count = count + 1
count = 8
while count <= 10:
    print(count)
    count = count + 1
"""

"""
# 正确
count = 1
while count <= 10:
    if count != 7:
        print(count)
    count = count + 1
"""

"""
# 正确
count = 1
while count <= 10:
    if count == 7:
        pass
    else:
        print(count)
    count = count + 1
"""

# 7. 关键字:break
"""
while True:
    print(666)
    break # 终止当前循环
print('结束')
"""
# 练习:
"""
# 通过break实现 1 ~ 10
count = 1
while True:
    print(count)
    if count == 10:
        break
    count = count + 1
print('结束')
"""

"""
# break是终止当前循环
while True:
    print('你好')
    while True:
        print(666)
        break
    break
"""

# 8. 关键字:continue
"""
count = 1
while count <=10:
    print(count)
    continue    # 本次循环如果遇到continue,则不在继续往下走,而是回到while条件位置。
    count = count + 1
"""

"""
示例:1234568910
count = 1
while count <=10:
    if count == 7:
        count = count + 1
        continue
    print(count)
    count = count + 1
"""

# 9. while else
"""
count = 1
while count < 10:
    print(count)
    count = count + 1
else: # 不再满足while后的条件时,触发。 或 条件=False
    print('ELSE代码块')

print('结束')
"""

"""
count = 1
while True:
    print(count)
    if count == 10:
        break
    count = count + 1
else: # 不再满足while后的条件时,触发。 或 条件=False
    print('ELSE代码块')
print('结束')
"""

字符串格式化

# 字符串格式化存在的意义
"""
name = input('姓名:')
do = input('在干什么:')
template = "%s在教室,%s。" %(name,do,)
print(template)
"""

# 直接做占位符
# template = "我是%s,年龄%s, 职业%s。" %("alex",73,'讲鸡汤',)
# print(template)


# template = "我是%s,年龄%d, 职业%s。" %("alex",73,'讲鸡汤',)
# print(template)

# name = 'alex'
# template = "%s现在手机的电量是100%%" %(name,)
# print(template)

# 练习
name = input('请输入姓名:')
age = input('请输入年龄:')
job = input('请输入职业:')
hobby = input('请输入爱好:')
msg = '''
------------ info of Alex Li ----------
Name  : %s
Age   : %s 
job   : %s 
Hobbie: %s 
------------- end ----------------'''

data = msg %(name,age,job,hobby,)
print(data)

运算符

# ####################### 算数运算符 #######################
# value = 11 % 3
# print(value)

# 练习题:打印 1 ~ 100 之间的奇数。
# count = 1
# while count <= 100:
#     val = count % 2
#     if val == 1:
#         print(count)
#     count = count + 1

# val = 2**8
# print(val)

# val = 9//2
# print(val)

# 练习题: 1 ~ 100 之间所有的数相加。
# total = 0
# count = 1
# while count <=100:
#     total = total + count
#     count = count + 1
# print(total)


# ####################### 赋值运算 #######################
# count = 1
# while count <=100:
#     print(count)
#     count +=1 # count = count + 1

# ####################### 逻辑运算 #######################
# 一般情况下
# if 1 > 0 and 1 > 2:
#     print('666')

# 二般情况下
## 小知识
# - int
# - str
# - bool

# 数字转字符串
# v1 = 666
# v2 = str(v1)
# 字符串转数字
# v1 = "666"
# v2 = int(v1)

# 数字转布尔值
# v1 = 0
# v2 = bool(v1)
# print(v2)

# 字符串转布尔值
# v1 = ""
# v2 = bool(v1)
# print(v2)

# 布尔值转换其他
# v1 = True
# v2 = str(v1)
# print(v2)

# 需要掌握的转换知识点
"""
    - 字符串转数字
    - 数字转字符串
    - "" / 0 转换布尔之后是False
"""


# 对于 or,如果有遇到
"""
    对于 or,如果有遇到 value= 1 or 9
    第一个值如果是转换成布尔值如果是真,则value=第一值。
    第一个值如果是转换成布尔值如果是假,则value=第二值。
    如果有多个or条件,则从左到右依次进行上述流程。
    示例:
        v1 = 0 or 1
        v2 = 8 or 10
        v3 = 0 or 9 or 8
"""

# 对于and,如果遇到
"""
    对于and,如果遇到 value= 1 and 9 这种情况
    如果第一个值转换成布尔值是True,则value=第二个值。
    如果第一个值转换成布尔值是False,则value=第一个值。
    如果有多个and条件,则从左到右依次进行上述流程。
    示例:
        v1 = 1 and 9
        v2 = 1 and 0
        v3 = 0 and 7
        v4 = 0 and ""
        v5 = 1 and 0 and 9
"""

# 综合
# 先看and再看or
# v1 = 1 and 9 or 0 and 6
# print(v1)
其他
1)优先级 在没有()的情况下not 优先级高于 and,and优先级高于or,即优先级关系为(
)>not>and>or,同一优先级从左往右计算。
2)数据类型转换

编码

编码扩展
ascii
unicode
ecs2
ecs4
utf-8,中文用3字节。
utf-16
# 先看and再看or
# v1 = 1 and 9 or 0 and 6
# print(v1)
# 数字转字符串
# v1 = 666
# v2 = str(v1)
# 字符串转数字
# v1 = "666"
# v2 = int(v1)
# 数字转布尔值
# v1 = 0
# v2 = bool(v1)
# print(v2)
# 字符串转布尔值
# v1 = ""
# v2 = bool(v1)
# print(v2)
# 布尔值转换其他
# v1 = True
# v2 = str(v1)
# print(v2)