Python 判断

# 判断
# 布尔值bool：True、False


# 相等判断
a = 5
b = 5
print(a == b) 


# 不相等判断
a = 5
b = 6
print(a!= b)  


# 大于、小于、大于等于、小于等于判断
a = 5
b = 6
print(a < b)  
print(a > b)  
print(a >= 5)  
print(b <= 6)  


# 判断是否包含特定元素
my_list = [1, 2, 3, 4]
print(3 in my_list)  
print(5 in my_list)  


my_string = "Hello, World!"
print("World" in my_string)  
print("Universe" in my_string)  


# 对于字典，可以判断键是否存在：
my_dict = {'name': 'John', 'age': 30}
print('name' in my_dict) 
print('gender' in my_dict)  


# 判断对象类型 isinstance()
a = 5
print(isinstance(a, int)) 
print(isinstance(a, str)) 


my_list = [1, 2, 3]
print(isinstance(my_list, list)) 


# 使用type()获取对象类型并进行比较
a = 5
print(type(a) == int)  
print(type(a) == str)  


my_list = [1, 2, 3]
print(type(my_list) == list)  


# if语句
age = 18
if age >= 18:
    print("You are an adult.")


# if - else语句
age = 16
if age >= 18:
    print("You are an adult.")
else:
    print("You are a minor.")




# if - elif - else语句
score = 75
if score >= 90:
    grade = 'A'
elif score >= 80:
    grade = 'B'
elif score >= 70:
    grade = 'C'
elif score >= 60:
    grade = 'D'
else:
    grade = 'F'
print("Your grade is:", grade)


# 嵌套if语句
num = 10
if num % 2 == 0:
    if num > 5:
        print("The number is an even number greater than 5.")
    else:
        print("The number is an even number less than or equal to 5.")
else:
    print("The number is odd.")




# 用于列表解析
a = [i^2 for i in range(10) if i%2==0]
print(a)


b = [i**2 for i in range(10) if i%2==0]
print(b)