Python控制流之循环控制详解(break, continue, pass)

# 遍历列表中的元素
numbers = [1, 2, 3, 4, 5]
for num in numbers:
    print(num)

# 打印从1到5的数字
i = 1
while i <= 5:
    print(i)
    i += 1

# 遇到数字3时终止循环
numbers = [1, 2, 3, 4, 5]
for num in numbers:
    if num == 3:
        break
    print(num)
# 输出: 1, 2

# 跳过数字3
numbers = [1, 2, 3, 4, 5]
for num in numbers:
    if num == 3:
        continue
    print(num)
# 输出: 1, 2, 4, 5

# 示例中什么也不做
for num in range(5):
    pass

class BankAccount:
    def __init__(self, account_number, balance=0):
        self.account_number = account_number
        self.balance = balance

    def deposit(self, amount):
        if amount > 0:
            self.balance += amount
            print(f"存款成功！当前余额: {self.balance}")
        else:
            print("存款金额必须大于零。")

    def withdraw(self, amount):
        if amount > self.balance:
            print("余额不足，无法取款。")
        elif amount <= 0:
            print("取款金额必须大于零。")
        else:
            self.balance -= amount
            print(f"取款成功！当前余额: {self.balance}")

    def display_balance(self):
        print(f"账户余额: {self.balance}")

def main():
    account = BankAccount("123456789", 1000)
    
    while True:
        print("\n银行账户管理系统")
        print("1. 存款")
        print("2. 取款")
        print("3. 查询余额")
        print("4. 退出")
        choice = input("请选择操作（1/2/3/4）：")

        if choice == '1':
            amount = float(input("请输入存款金额："))
            account.deposit(amount)
        elif choice == '2':
            amount = float(input("请输入取款金额："))
            account.withdraw(amount)
        elif choice == '3':
            account.display_balance()
        elif choice == '4':
            print("退出系统。")
            break
        else:
            print("无效的选择，请重新输入。")
            continue

if __name__ == "__main__":
    main()

while True:
    user_input = input("请输入一个数字（输入'退出'以结束）：")
    if user_input == "退出":
        break
    try:
        number = float(user_input)
        print(f"你输入的数字是 {number}")
    except ValueError:
        print("无效的输入，请输入一个数字。")

# 只打印奇数
for num in range(10):
    if num % 2 == 0:
        continue
    print(num)
# 输出: 1, 3, 5, 7, 9

for i in range(5):
    if i == 2:
        pass  # 将来可能会添加代码
    else:
        print(i)
# 输出: 0, 1, 3, 4