第一章语言基础
第一节编程基础
1 python开发环境
第一个Python程序
# 打印"Hello World"
print("Hello World")
# 打印2的100次方
print(2 ** 100)
# 打印1+1=2
print("1+1=",1 + 1)
"""
Hello World
1267650600228229401496703205376
1+1= 2
"""
利用Python编写自己的第一个Python程序(自由发挥)
print("我是python，你是谁？")
a = input()
print("我知道了，你是",a)
"""
我是python，你是谁？
小潘
我知道了，你是 小潘
"""
2 python输入与输出
# 默认以空格分隔，默认以换行结尾
print("Hello","World",123,sep = '+')
print("Hello","World",123,sep = '-')
print("Hello","World",123)
print('-'*20)
print("Hello","World",123,sep = '+',end='?')
print("Hello","World",123,sep = '-')
print("Hello","World",123,end="apple")
print("11111")
"""
Hello+World+123
Hello-World-123
Hello World 123
--------------------
Hello+World+123?Hello-World-123
Hello World 123apple11111
"""print(1)
print("Hello World")
a = 1
b = 'running'
print(a,b)
print("aaa""bbb")
print("aaa","bbb")
print("www","lanqiao","cn",sep='.')
"""
1
Hello World
1 running
aaabbb
aaa bbb
www.lanqiao.cn
"""a = input() # 输入整数123，input()函数把输入的都转换成字符串
print(type(a)) # 输出a的类型
a = int(a) # 转换成整数
print(type(a)) # 输出a的类型
a = input("input:") #输入字符串Hello
print(type(a)) # 输出a的类型
"""
123
<class 'str'>
<class 'int'>
input:Hello
<class 'str'>
"""
# 输入三条边的长度
a = int(input("第一条边为："))
b = int(input("第一条边为："))
c = int(input("第一条边为："))
# 计算半周长
p = (a+b+c)/2
s = p*(p-a)*(p-b)*(p-c)
s = s**0.5
# 输出面积
print("三角形面积是：",s)
"""
第一条边为：3
第一条边为：4
第一条边为：5
三角形面积是： 6.0
"""
a = int(input("请输入a的值："))
b = int(input("请输入b的值："))
# 检查输入是否为正整数
if a <= 0 or b <= 0:
print("输入的必须是正整数。")
else:
print("a+b=", a + b)
print("a-b=", a - b)
print("a*b=", a * b)
print("a/b=", a / b)
print("a^b=", a ** b)
"""
a,b = int(input("何时开始")),int(input("何分开始"))
c,d = int(input("何时停止")),int(input("何分停止"))
"""
a = int(input("何时开始"))
b = int(input("何分开始"))
c = int(input("何时停止"))
d = int(input("何分停止"))
e = c - a
f = d - b
print("总共游泳：",e*60+f,"分钟")
"""
何时开始12
何分开始0
何时停止13
何分停止1
总共游泳： 61 分钟
"""3 常量、变量与运算符
a = 2 + 3
print(a)
a = 3 - 2
print(a)
a = 3/2
print(a)
a = 3**2
print(a)
a = 0.1 + 0.1
print(a)
a = 0.1 + 0.2
print(a)
a = 0.1 * 3
print(a)
"""
age = 23
message = "Happy " + age + "rd Birthday!"
print(message)
"""
age = 23
message = "Happy " + str(age) + "rd Birthday!"
print(message)
print(type(message))
"""
5
1
1.5
9
0.2
0.30000000000000004
0.30000000000000004
Happy 23rd Birthday!
<class 'str'>
"""a = 3.7
print(a,type(a))
a = int(a)
print(a,type(a))
a = -1.5
print(a,type(a))
a = int(a)
print(a,type(a))
a = 1.9999
print(a,type(a))
a = int(a)
print(a,type(a))
a = 1.9999 + 0.001
print(a,type(a))
a = int(a)
print(a,type(a))
"""
3.7 <class 'float'>
3 <class 'int'>
-1.5 <class 'float'>
-1 <class 'int'>
1.9999 <class 'float'>
1 <class 'int'>
2.0009 <class 'float'>
2 <class 'int'>
"""a = 5
print(a,type(a))
a = bool(a)
print(a,type(a))
a = 0
print(a,type(a))
a = bool(a)
print(a,type(a))
a = 0.0
print(a,type(a))
a = bool(a)
print(a,type(a))
a = -1
print(a,type(a))
a = bool(a)
print(a,type(a))
a = True
print(a,type(a))
a = bool(a)
print(a,type(a))
a = True
print(a,type(a))
a = str(a)
print(a,type(a))
"""
5 <class 'int'>
True <class 'bool'>
0 <class 'int'>
False <class 'bool'>
0.0 <class 'float'>
False <class 'bool'>
-1 <class 'int'>
True <class 'bool'>
True <class 'bool'>
True <class 'bool'>
True <class 'bool'>
True <class 'str'>
"""
a = 10
print("a=",a,"type(a)=",type(a))
print("float(a)=",float(a),"type(float(a))=",type(float(a)))
print("bool(a)=",bool(a),"type(bool(a))=",type(bool(a)))
print()
b = 7.8
print("b=",b,"type(b)=",type(b))
print("str(b)=",int(b),"type(str(b))=",type(int(b)))
print("str(b)=",str(b),"type(str(b))=",type(str(b)))
print()
c = "12.3"
print("c=",c,"type(c)=",type(c))
print("float(c)=",float(c),"type(float(c))=",type(float(c)))
"""
a= 10 type(a)= <class 'int'>
float(a)= 10.0 type(float(a))= <class 'float'>
bool(a)= True type(bool(a))= <class 'bool'>
b= 7.8 type(b)= <class 'float'>
str(b)= 7 type(str(b))= <class 'int'>
str(b)= 7.8 type(str(b))= <class 'str'>
c= 12.3 type(c)= <class 'str'>
float(c)= 12.3 type(float(c))= <class 'float'>
"""
a = 25
b = 10
# 除法运算符
c = a/b
print(c,type(c))
# 整除运算符
c = a//b
print(c,type(c))
# 转换成浮点数
c = float(c)
print(c,type(c))
"""
2.5 <class 'float'>
2 <class 'int'>
2.0 <class 'float'>
"""
a = 25
b = 10
# 关系运算符，运算结果为True或者False
c = a == b
print(c,type(c))
c = a > b
print(c,type(c))
c = a < b
print(c,type(c))
"""
False <class 'bool'>
True <class 'bool'>
False <class 'bool'>
"""
a = 25
b = 10
#赋值运算符，将等号右边的运算结果存入等号左边的变量
c = a + b
print(c,type(c))
# c = c + a
c += a
print("c=",c)
# c = c/a
c /= a
print("c=",c)
"""
35 <class 'int'>
c= 60
c= 2.4
"""
a = 25
b = 10
# 并且：两者均为True才为True
c = a > 0 and b > 0
print(c)
# 或者：只要有一者为True即为True
c = a < 0 or b > 5
print(c)
# 非，not，True -> False,False -> True
c = not a
print(c)
"""
True
True
False
"""
def calculator():
while True:
try:
# 输入第一个操作数
operand1 = input("请输入第一个操作数（可以是整数、浮点数、字符串或布尔值）：")
operand1 = eval(operand1)
# 输入运算符
operator = input("请输入运算符（+、-、*、/、//、%、**、==、!=、>、<、>=、<=、and、or、not、in、is、is not）：")
# 输入第二个操作数
operand2 = input("请输入第二个操作数（可以是整数、浮点数、字符串或布尔值）：")
operand2 = eval(operand2)
# 执行运算
if operator == "+":
result = operand1 + operand2
elif operator == "-":
result = operand1 - operand2
elif operator == "*":
result = operand1 * operand2
elif operator == "/":
if operand2 == 0:
print("错误：除数不能为零")
continue
result = operand1 / operand2
elif operator == "//":
if operand2 == 0:
print("错误：除数不能为零")
continue
result = operand1 // operand2
elif operator == "%":
if operand2 == 0:
print("错误：除数不能为零")
continue
result = operand1 % operand2
elif operator == "**":
result = operand1 ** operand2
elif operator == "==":
result = operand1 == operand2
elif operator == "!=":
result = operand1 != operand2
elif operator == ">":
result = operand1 > operand2
elif operator == "<":
result = operand1 < operand2
elif operator == ">=":
result = operand1 >= operand2
elif operator == "<=":
result = operand1 <= operand2
elif operator == "and":
result = operand1 and operand2
elif operator == "or":
result = operand1 or operand2
elif operator == "not":
result = not operand1
elif operator == "in":
if isinstance(operand1, (list, tuple, str)) and operand2 in operand1:
result = True
else:
result = False
elif operator == "is":
result = operand1 is operand2
elif operator == "is not":
result = operand1 is not operand2
else:
print("未知运算符")
continue
# 输出结果
print(f"结果：{result}")
except Exception as e:
print(f"发生错误：{e}")
continue
# 询问是否继续或退出
continue_calc = input("是否继续计算？(y继续/n退出)：")
if continue_calc.lower() == 'n':
print("退出程序")
break
if __name__ == "__main__":
calculator()第二节选择结构
1条件表达式和逻辑表达式
条件表达式
a,b,c,d = 5,6,7,5
e = a > b
f = a < c
g = a != d
h = a + 1 >= b
print(e)
print(f)
print(g)
print(h)
"""
False
True
False
True
"""逻辑表达式
a = 5
b = not a # False
c = not b # True
d = not(a and c) # False
e = ((c - 1) or (d + 1)) # 1
f = ((c - 1) or (d + 2)) # 2
print(b,c,d,e,f)
print(type(e)) # <class 'int'>
url = "Hello World"
print("False and xxx")
print(False and print(url))
print()
print("True and xxx")
print(print((url)))
print(True and print((url)))
print()
print("False or xxx")
print(False or print(url))
print()
print("True or xxx")
print(print((url)))
print(True or print((url)))
print()
"""
False and xxx
False
True and xxx
Hello World
None
Hello World
None
False or xxx
Hello World
None
True or xxx
Hello World
None
True
"""
# 算术运算符>关系运算符>逻辑运算符>赋值运算符
x = 1>1 or 3<4 or 4>5 and 2>1 and 9>8 or 7<6
print(x)
x = 1>1 or print("111") or 3<4 or 4>5 and 2>1 and 9>8 or 7<6
print(x)
x = 1>1 or 3<4 or print("111") or 4>5 and 2>1 and 9>8 or 7<6
print(x)
"""
True
111
True
True
"""
# not是单目运算符，优先级较高
x = not 2>1 and 3<4 or 4>5 and 2>1 and 9>8 or 7<6
# x = (not 2)>1 and 3<4 or 4>5 and 2>1 and 9>8 or 7<6
# x = 0>1 and 3<4 or 4>5 and 2>1 and 9>8 or 7<6
# x = False or 4>5 and 2>1 and 9>8 or 7<6
# x = False and 2>1 and 9>8 or 7<6
# x = False and 9>8 or 7<6
# x = False or 7<6
# x = False
print(x) # False
a = int(input())
b = int(input())
c = int(input())
d = a == 100 or b == 100 or c ==100
e = (a>90 and b>90) or (a>90 and c>90) or (b>90 and c>90)
f = a>80 and b>80 and c>80
answer = d or e or f
print(answer)
"""
70
70
70
False
""" 
