请教一下 这该怎么做 学了一天 没有一点头绪

学了一天没有一点头绪 .到底该怎么做初学者实在搞不懂 . 刚接触还有好多不懂

# 定义初始库存数据：列表中有三个字典，每个字典代表一种水果，包括名称、单价和数量
inventory = [
    {'name': '苹果', 'price': 3.5, 'count': 100},
    {'name': '香蕉', 'price': 2.8, 'count': 50},
    {'name': '橙子', 'price': 4.0, 'count': 80}
]

# 欢迎程序：根据输入的水果名称返回水果信息，如果不存在则返回“该水果不存在”
def welcome():
    name = input("欢迎来到美味水果店！请输入要查询的水果名称：")
    for fruit in inventory:
        if name == fruit['name']:
            print("本店有水果：{name}，单价为{price}元，库存为{count}斤".format(**fruit))
            return
    print("该水果不存在")

# 添加水果程序：向库存添加新的水果信息
def add_fruit():
    name = input("请输入水果名称：")
    price = float(input("请输入水果单价："))
    count = int(input("请输入水果库存数量："))
    new_fruit = {'name': name, 'price': price, 'count': count}
    inventory.append(new_fruit)
    print("添加成功！")

# 修改水果信息程序：根据输入的水果名称修改单价或库存信息
def modify_fruit():
    name = input("请输入要修改的水果名称：")
    for fruit in inventory:
        if name == fruit['name']:
            price = input("请输入新的单价（直接回车表示不修改）：")
            if price:
                fruit['price'] = float(price)
            count = input("请输入新的库存数量（直接回车表示不修改）：")
            if count:
                fruit['count'] = int(count)
            print("修改成功！")
            return
    print("该水果不存在")

# 购买水果程序：根据输入的水果名称和购买数量计算出总金额
def buy_fruit():
    name = input("请输入要购买的水果名称：")
    for fruit in inventory:
        if name == fruit['name']:
            count = int(input("请输入购买数量："))
            if count > fruit['count']:
                print("库存不足！")
                return
            price = fruit['price'] * count
            print("您需要支付{price}元。".format(price=price))
            fruit['count'] -= count
            return
    print("该水果不存在")

# 展示当前库存信息程序：展示目前所有水果的库存信息
def show_inventory():
    print("现有库存商品为：")
    print("name    price   count")
    for fruit in inventory:
        print("{name}     {price}      {count}".format(**fruit))

# 选择功能程序：显示菜单并根据用户输入调用相应程序
def choose_action():
    while True:
        print("欢迎来到美味水果店")
        print("请输入您要进行的操作：")
        print("1--查询")
        print("2--添加")
        print("3--修改")
        print("4--购买")
        print("5--展示")
        print("其他--退出系统")
        choice = input()
        if choice == '1':
            welcome()
        elif choice == '2':
            add_fruit()
        elif choice == '3':
            modify_fruit()
        elif choice == '4':
            buy_fruit()
        elif choice == '5':
            show_inventory()
        else:
            break

# 主程序：调用选择功能程序
choose_action()

fruit_shop = [
    {"name": "apple", "price": 2.0, "count": 10},
    {"name": "banana", "price": 3.5, "count": 5},
    {"name": "orange", "price": 1.5, "count": 8},
    {"name": "grape", "price": 4.0, "count": 12}
]

#添加新水果:

def add_fruit(fruit_shop, name, price, count):
    for fruit in fruit_shop:
        if name == fruit["name"]:
            print(f"{name} already exists. Try modifying its price or count instead.")
            return fruit_shop
    fruit_shop.append({"name": name, "price": price, "count": count})
    print(f"{name} has been added to the inventory.")
    return fruit_shop

#修改现有的水果名价格数量：

def modify_fruit(fruit_shop, name, price=None, count=None):
    for fruit in fruit_shop:
        if name == fruit["name"]:
            if price is not None:
                fruit["price"] = price
            if count is not None:
                fruit["count"] = count
            print(f"{name} has been modified.")
            return fruit_shop
    print(f"{name} does not exist in the inventory.")
    return fruit_shop

#查询某个水果是否存在:

def search_fruit(fruit_shop, name):
    for fruit in fruit_shop:
        if name == fruit["name"]:
            print(f"{name} exists in the inventory.")
            return fruit
    print(f"{name} does not exist in the inventory.")
    return None

输出当前库存:

def display_inventory(fruit_shop):
    print("Current Inventory:")
    for fruit in fruit_shop:
        print(f"Name: {fruit['name']}, Price: {fruit['price']}, Count: {fruit['count']}")

#购买水果计算总价:

def purchase_fruit(fruit_shop, name, quantity):
    fruit = search_fruit(fruit_shop, name)
    if fruit is not None:
        if fruit["count"] < quantity:
            print(f"Sorry, we only have {fruit['count']} {name}(s) left.")
            return None
        else:
            fruit["count"] -= quantity
            total_price = quantity * fruit["price"]
            print(f"You have purchased {quantity} {name}(s) for a total of ${total_price:.2f}.")
            return total_price

def main():
    fruit_shop = [
        {"name": "apple", "price": 2.0, "count": 10},
        {"name": "banana", "price": 3.5, "count": 5},
        {"name": "orange", "price": 1.5, "count": 8},
        {"name": "grape", "price": 4.0, "count": 12}
    ]

    print("Welcome to our Fruit Shop!")
    display_inventory(fruit_shop)

    add_fruit(fruit_shop, "pear", 2.5, 6)
    modify_fruit(fruit_shop, "orange", price=2.0, count=10)

    search_fruit(fruit_shop, "banana")

    display_inventory(fruit_shop)

    purchase_fruit(fruit_shop, "apple", 3)
    purchase_fruit(fruit_shop, "kiwi", 2)

if __name__ == '__main__':
    main()

主体部分用一个while True：不断地弹出菜单，输入非1-5时跳出循环

以下内容由CHATGPT及阿里嘎多学长共同生成、有用望采纳：

首先，建议你先掌握Python的基础语法，包括变量、数据类型、运算符、条件语句、循环语句等等。可以通过阅读Python教材或者网上的Python教程来学习。

针对你提出的问题，你可以先了解Python中的字符串操作。Python中的字符串可以通过索引访问单个字符，也可以通过切片获取子串。下面是一些字符串操作的示例代码：

# 定义字符串
s = "hello world"

# 获取字符串长度
print(len(s))  # 输出 11

# 获取第一个字符
print(s[0])  # 输出 h

# 获取最后一个字符
print(s[-1])  # 输出 d

# 获取子串
print(s[0:5])  # 输出 hello

# 检查字符串是否包含某个子串
print("world" in s)  # 输出 True

# 将字符串转换为大写或小写
print(s.upper())  # 输出 HELLO WORLD
print(s.lower())  # 输出 hello world

另外，你还可以了解Python中的列表、字典、函数等概念和用法，这些都是Python中非常重要的概念。希望这些内容能对你有所帮助。