掌握 Python 的七种常用数据类型

# 定义一个整数  
a = 10  
b = -5  

# 输出整数  
print(a)  # 输出: 10  
print(b)  # 输出: -5  

# 整数运算  
sum = a + b  
print(sum)  # 输出: 5  
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# 定义一个浮点数  
pi = 3.14  
gravity = 9.81  

# 输出浮点数  
print(pi)        # 输出: 3.14  
print(gravity)   # 输出: 9.81  

# 浮点数运算  
area = pi * (5 ** 2)  # 计算半径为5的圆的面积  
print(area)  # 输出: 78.5  
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# 定义一个字符串  
greeting = "Hello, World!"  
quote = 'To be or not to be, that is the question.'  
multiline = """This is a multi-line  
string."""  

# 输出字符串  
print(greeting)        # 输出: Hello, World!  
print(quote)           # 输出: To be or not to be, that is the question.  
print(multiline)       # 输出:  
                       # This is a multi-line  
                       # string.  

# 字符串操作  
length = len(greeting)  
print(length)  # 输出: 13  
upper_greeting = greeting.upper()  
print(upper_greeting)  # 输出: HELLO, WORLD!  
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# 定义布尔值  
is_raining = True  
is_sunny = False  

# 输出布尔值  
print(is_raining)  # 输出: True  
print(is_sunny)    # 输出: False  

# 布尔运算  
and_result = is_raining and is_sunny  
or_result = is_raining or is_sunny  
print(and_result)  # 输出: False  
print(or_result)   # 输出: True  
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# 定义一个列表  
fruits = ['apple', 'banana', 'cherry']  
numbers = [1, 2, 3, 4, 5]  
mixed_list = [1, 'two', 3.0, True]  

# 输出列表  
print(fruits)         # 输出: ['apple', 'banana', 'cherry']  
print(numbers)        # 输出: [1, 2, 3, 4, 5]  
print(mixed_list)     # 输出: [1, 'two', 3.0, True]  

# 列表操作  
fruits.append('date')  
print(fruits)  # 输出: ['apple', 'banana', 'cherry', 'date']  
length = len(numbers)  
print(length)  # 输出: 5  
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# 定义一个元组  
coordinates = (10, 20)  
colors = ('red', 'green', 'blue')  

# 输出元组  
print(coordinates)  # 输出: (10, 20)  
print(colors)       # 输出: ('red', 'green', 'blue')  

# 元组是不可变的  
# coordinates[0] = 15  # 这行代码会引发错误  
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# 定义一个字典  
person = {  
    'name': 'Alice',  
    'age': 30,  
    'city': 'New York'  
}  

# 输出字典  
print(person)  # 输出: {'name': 'Alice', 'age': 30, 'city': 'New York'}  

# 访问字典中的值  
name = person['name']  
print(name)  # 输出: Alice  

# 修改字典中的值  
person['age'] = 31  
print(person)  # 输出: {'name': 'Alice', 'age': 31, 'city': 'New York'}  

# 添加新的键值对  
person['job'] = 'Engineer'  
print(person)  # 输出: {'name': 'Alice', 'age': 31, 'city': 'New York', 'job': 'Engineer'}  
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# 定义一个字典来存储学生信息  
students = {  
    'Alice': {'age': 20, 'grades': [85, 90, 88]},  
    'Bob': {'age': 22, 'grades': [78, 82, 85]},  
    'Charlie': {'age': 21, 'grades': [92, 95, 90]}  
}  

# 查询学生信息  
def query_student(student_name):  
    if student_name in students:  
        student_info = students[student_name]  
        print(f"Name: {student_name}")  
        print(f"Age: {student_info['age']}")  
        print(f"Grades: {student_info['grades']}")  
        average_grade = sum(student_info['grades']) / len(student_info['grades'])  
        print(f"Average Grade: {average_grade:.2f}")  
    else:  
        print(f"Student {student_name} not found.")  

# 更新学生成绩  
def update_grade(student_name, subject_index, new_grade):  
    if student_name in students:  
        if 0 <= subject_index < len(students[student_name]['grades']):  
            students[student_name]['grades'][subject_index] = new_grade  
            print(f"Updated grade for {student_name} in subject {subject_index} to {new_grade}.")  
        else:  
            print(f"Invalid subject index for {student_name}.")  
    else:  
        print(f"Student {student_name} not found.")  

# 示例操作  
query_student('Alice')  
update_grade('Bob', 1, 88)  
query_student('Bob')  
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Name: Alice  
Age: 20  
Grades: [85, 90, 88]  
Average Grade: 87.67  
Updated grade for Bob in subject 1 to 88.  
Name: Bob  
Age: 22  
Grades: [78, 88, 85]  
Average Grade: 83.67  
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