# 基本if語句
age = 18
if age >= 18:
    print("您已成年")

# if-else語句
if age >= 18:
    print("您已成年")
else:
    print("您未成年")

# if-elif-else語句
if age < 12:
    print("兒童")
elif age < 18:
    print("青少年")
else:
    print("成年人")

注意事項：

• Python使用縮進來區分代碼塊
• 冒號(:)後必須縮進
• 建議使用4個空格作為縮進

# 常用比較運算符
x = 10
y = 5

if x > y:    # 大於
    print("x大於y")
    
if x >= y:   # 大於等於
    print("x大於等於y")
    
if x < y:    # 小於
    print("x小於y")
    
if x <= y:   # 小於等於
    print("x小於等於y")
    
if x == y:   # 等於
    print("x等於y")
    
if x != y:   # 不等於
    print("x不等於y")

# and運算符
age = 25
income = 30000
if age >= 18 and income >= 25000:
    print("符合貸款條件")

# or運算符
if age < 18 or income < 25000:
    print("不符合貸款條件")

# not運算符
is_student = True
if not is_student:
    print("非學生身份")

score = int(input("請輸入分數："))

if score >= 90:
    grade = "A"
elif score >= 80:
    grade = "B"
elif score >= 70:
    grade = "C"
elif score >= 60:
    grade = "D"
else:
    grade = "F"

print(f"您的等級是：{grade}")

price = float(input("請輸入商品價格："))
is_member = input("是否是會員？(y/n)：") == "y"

if is_member:
    if price >= 1000:
        discount = 0.8
    else:
        discount = 0.9
else:
    if price >= 1000:
        discount = 0.9
    else:
        discount = 1.0

final_price = price * discount
print(f"最終價格：{final_price:.2f}")

# 一般寫法
if age >= 18:
    status = "成年"
else:
    status = "未成年"

# 條件表達式寫法
status = "成年" if age >= 18 else "未成年"

day = "星期一"
time = 14

if day in ["星期六", "星期日"]:
    print("週末")
elif 9 <= time <= 18 and day not in ["星期六", "星期日"]:
    print("工作時間")
else:
    print("休息時間")