import datetimeimport calendar#第一個例子：#算一下還有多久能還清信用卡#定義信用卡待還總額10000元balance = 10000#定義利率為13%interest_rate = 13 * .01#定義每個月還500元monthly_payment = 500#獲取今天today = datetime.date.today()#print(today)#獲取本月有多少天days_in_current_month = calendar.monthrange(today.year,today.month)[1]#返回一個元組#第一個參數是本周的第幾天#第二個參數是本月有多少天print(days_in_current_month)#獲取還有幾天到月末days_till_end_month = days_in_current_month - today.dayprint(days_till_end_month)#獲取下個月的開始日期#作為我們第一次還款月start_date = today + datetime.timedelta(days=days_till_end_month + 1) print(start_date)#定義還款日期等于開始還款日期end_date = start_datewhile balance >0:  #獲取產生利息的費用  interest_charge = (interest_rate / 12) * balance  #需要還款的總額  balance += interest_charge  #減去已還額度，剩余待還  balance -=monthly_payment  #四舍五入保留兩位小數字  balance = round(balance,2)   if balance < 0:    balance = 0  #打印還款月，剩余待還金額  print(end_date,balance)  #獲取還款月的總天數  days_in_current_month = calendar.monthrange(end_date.year,end_date.month)[1]  #獲取下一還款月  end_date = end_date + datetime.timedelta(days=days_in_current_month) 
#運行就可以查看到需要多少個月還清信用卡了
#第二個例子：#算一下多少周可以減肥到目標體重#當前體重150斤current_weight = 150#目標體重100斤goal_weight = 100#假設一周減掉1.5斤avg_lose_weight_week = 1.5#獲取開始日期 start_date = datetime.date.today()#定義達到目標體重的結束日期end_date = start_datewhile current_weight > goal_weight:  current_weight -= avg_lose_weight_week  end_date  += datetime.timedelta(days=7) print(end_date)print(f'達到目標體重需要{(end_date - start_date).days // 7} 周！')
#第三個例子#計算什么時間粉絲可以達到100000#目標粉絲數量goal_subs = 100000#當前粉絲數量current_subs = 85000#還需多少粉絲到目標subs_to_goal = goal_subs - current_subs#假設每天粉絲增長為200個avg_subs_day = 200import math#計算需要多少天達到目標days_to_goal = math.ceil(subs_to_goal/avg_subs_day) #計算哪天達到目標today = datetime.date.today()goal_subs_date = today + datetime.timedelta(days=days_to_goal)print(goal_subs_date)