Python_day1

 

• Python历史背景

Guido van rossum "龟叔, 1989年
"简单，明确，优雅"
解释型语言
高级语言

• Python的基本数据类型

内置类型:
　　　　布尔类型：True False
　　　　数字类型：int float
　　　　文本类型：str
　　　　序列类型：list tuple range
　　　　集合类型：set
　　　　映射类型：dict

1.布尔类型：True False

2.数字类型：int float

# 定义一个整型变量
a = 1
b = int(100)
s = '100'
s = int(s) # 强转
print(type(s))


print(type(a))
print(type(b))

a = 10.2
print(type(a))

运算符优先级：

单目运算符：~ + -(正负)

算术运算符：** / * // % + -

位运算符：& | ^ >> <<

关系运算符：> >= < <= == !=

赋值运算符：= += -= /= *= //= %= **=

身份运算符：is is not

成员运算符：in not in

逻辑运算符：not and or

位运算符：& | ^ >> <<

# 位运算(& | ^ ~ << >>)
a = '100'
print(int(a, 2))
b = 100
print(bin(b))
c = 66
print(bin(c))
print(b & c)
print(b | c)
print(b ^ c)

关系运算符：> >= < <= == !=

# 关系运算符(> >= < <= == !=) 逻辑运算符(not and or)
print(10 > 100)
print(10 > 3 and 10 < 5)
print(-8 and 5)
print(0 and 5)
print(5 and 100)
print(5 and 100 < 5)
print(0 and 100 < 5)
print(10 > 5 and 2)
print('**********************')
print(-8 or 5)
print(0 or 5)
print(5 or 100)
print(5 or 100 < 5)
print(0 or 100 < 5)
print(10 > 5 or 2)
print('**********************')
print(10 and 5 or 0)
print(10 or 5 and 0)
print(not 5 and 10 > 5 or 100)
a = 100
b = a
print(a is b)
print(a, b)
a = 200
b = 200
print(a is b)
print(a, b)

赋值运算符：= += -= /= *= //= %= **=

# 赋值运算
# a = a + 2
a += 2 # -= *= /= //= %=
print(a)
print(1+True)

身份运算符：is is not

成员运算符：in not in
逻辑运算符：not and or

a = 10
b = 3.0
print(a + b)
print(a - b)
print(a * b)
print(a / b)
print(a // b)
print(a % b)
print(a ** b)

函数:

int()
divmod()
abs()

# 函数
print(abs(-100))
print(pow(2, 8))
print(divmod(8, 3))

3.字符串:str

定义：'' "" '''''' """"""

# 字符串类型

# 定义
s1 = 'hi'
s2 = "hello"
s3 = """moring"""
s4 = '''moring
good'''

print(s1, s2, s3, s4)

s = str(100)
print(type(s))

　运算符:：+ / *n / in / not in 

# 字符串中应用的运算符
print(s1 + s2)

print(s1 * 5)

s1 += s2
print(s1, s2)

# 成员运算符
print('hi' in s1)
print('hg' not in s1)

有序的----》索引(0) "abc"

s[index] 0<= index < len(s) -len(s)<= index <= -1
切片:
s[start:end:step]
start<= index < end----> index += step

# 索引和切片 正向递增(0~len(s)-1) 反向递减(-1~-len(s))
s = 'python'
print(s[0])
print(s[-1])

print(s[1:3]) # s[a:b] a<=<b s[start=0:end=len(s):step=1]

print(s[-3:-1])

print(s[-1:-3:-1])

print(s[:3])

print(s[:])

print(s[::2])

函数:

len()

max() / min() / .index() / .count()

# 函数
print(s[len(s)-1])
print(max(s))
print(min(s))
print(s.index('h'))
print(s.count('n'))

.format()

# 格式化字符串
n = 5
s = '我今天瘦了%d两'% n
print(s)
print('我今天%s高兴' % '很')

height=169
weight=80.5
print('我的身高是{}cm,体重是{}kg'.format(height, weight))
print('我的身高是{1}cm,体重是{0}kg'.format(weight, height))

name = 'python'
age = 29
print('我的名字{nameid}, 年龄是{ageid}'.format(ageid=age, nameid=name))

s = '我太帅了'
print('{:*>20}'.format(s))
print('{:*<20}'.format(s))
print('{:*^20}'.format(s))

f = 10.8998765
print('{:.2f}'.format(f))

4.序列类型：list tuple range

5.集合：set

6.映射类型：dict

• 读入和输出

input()
print()

# 读入
s = input('请说的什么:')
print(type(s))
print(s)

n = int(s)
print(type(n), n)

s = input('请输入两个整型数:')
print(s)

a, b = eval(s) # 将字符串'num1, num2'转换为整型数num1, num2
print(a, b)

# 两个数的交换
b = b ^ c
c = b ^ c
b = b ^ c
print(b, c)

a = 4
print(a << 2)
print(a >> 2)