🐍 综合练习：计算年龄

扩展：input 输入生日，格式化输出。

# ========================================
# 示例：根据生日算年龄
# 说明：简化算法，精确业务需考虑是否过生日
# ========================================
from datetime import datetime

def age(birth_str):
    birth = datetime.strptime(birth_str, '%Y-%m-%d')
    today = datetime.now()
    years = today.year - birth.year
    if (today.month, today.day) < (birth.month, birth.day):
        years -= 1
    return years

print('年龄', age('2010-06-01'), '岁')