【Python】字符串，数

# 字符串支持单引号和双引号
message1 = 'Hello!'
message2 = "Hello Python World!"
print(message1)
print(message2)

# 混用可以实现存储单or双引号
message = "The language 'python' is named after Monty Python, not the snake."
print(message)

# 每个单词首字母大写
name = "ada lovelace"
print(name.title())
# 字符串全部大写or小写
print(name.upper())
print(name.lower())

favorite_language = ' python '
print("'"+favorite_language+"'")
# 删除字符串末尾的空白
print("'"+favorite_language.rstrip()+"'")
# 删除字符串开头的空白
print("'"+favorite_language.lstrip()+"'")
# 删除字符串两头的空白
print("'"+favorite_language.strip()+"'")

# 字符串中使用变量的值：f字符串
first_name = "ada"
last_name = "lovelace"
full_name = f"{first_name} {last_name}"
print(f"Hello, {full_name.title()}!")

"""
1：整数
"""
# 加减乘除
print(2+3)
print(6-9)
print(5*5)
print(4/3)  # 两数相除总是浮点数

print("-----------------")
# 乘方
print(3**2)

print("-----------------")
"""
2：浮点数
"""
# 加减乘除
print(0.1+0.1)
print(0.04-0.06)
print(2*0.1)
print(0.06/2)  # 两数相除总是浮点数

print("-----------------")
"""
3：整数和浮点数
"""
print(1+0.2)
print(2-0.03)
print(3.0**2)

# 使用下划线表示很大的数
universe_age = 14_000_000_000
print(universe_age)


# python没有内置的常量类型,一般使用全大写指出某数为常量
MAX_ConNECTIONS = 5000

# 同时给多个数赋值
x, y, z = 0, 0, 0
print(x, y, z)

# 是否相等,不等
age = 17
print(age == 18)
print(age != 18)

# 且,或
age_0 = 22
age_1 = 18
print(age_0 >= 21 and age_1 >= 21)
print(age_0 >= 21 or age_1 >= 21)