投資計算器拒絕正確計算

Question

我的程序運行但絕對不是它的本意。 無論我輸入哪個，它總是說“你賺了：0.00 美元”，我嘗試將“months_invested = years_investment / 12”移動到多個地方，甚至添加或刪除位。

投資計算器旨在每月計算這些東西，但我似乎無法正確計算。 一個問題變成兩個問題，這對我來說就像九頭蛇，你解決了一件事情，它就會成倍增加。

"""

 InvestmentCalculator.py helps generate how much interest one earns after a certain period of time
 """


 def main():
     total_money = 0
     months_invested = 0
     years_investment = 0

 investment = float(input("How much would you like to invest? "))
 years_investment = float(input("How many years would you like to invest? "))
 interest_rate = float(input("What is the interest rate? "))
 total_money = float()
 months_invested = float()


 while months_invested > 0:
     months_invested = (years_investment / 12) - 1
     total_money = investment +  total_money
     print("You have earned ${:,.2f}".format(total_money))
 else: print("You've earned a total of ${:,.2f}".format(total_money))


 main()

Answer 1

我有一種感覺，這就是您要實現的目標。 需要進行一些調整，我將在代碼下方進行解釋：

def main():    
    total_money = float(input("How much would you like to invest? "))
    years_investment = float(input("How many years would you like to invest? "))
    interest_rate = float(input("What is the monthly interest rate in %? "))

    months_invested = years_investment * 12
    while months_invested > 0:
        interests = interest_rate / 100 * total_money
        total_money += interests
        print("You have earned ${:,.2f}".format(total_money))
        months_invested += -1

main()

輸出：

You have earned $101.00
You have earned $102.01
You have earned $103.03
You have earned $104.06
You have earned $105.10
You have earned $106.15
You have earned $107.21
You have earned $108.29
You have earned $109.37
You have earned $110.46
You have earned $111.57
You have earned $112.68

正如 G.Anderson 所說，沒有必要用值 0（或任何值）初始化變量。 只需將其定義為輸入即可。

月投資公式錯誤，困擾循環。 此外，如果這是固定的，循環將無限運行，因為沒有限制或條件可以結束它（這就是months_invested += -1的目的。每次循環通過時減少變量的值，以便它停止某個時候（也就是說，當沒有更多的投資月份時）。

最后記住你的函數正在打印結果而不返回任何東西，所以提前使用它時要小心。

如果您需要復利（每月），那么您應該使用復利公式。 即(((1+i) ** months) -1) * $ 。 在這種情況下，我使用total_money += interests將期間產生的利息加到資金總額中，這些資金將在下一期間再投資（因此，復利）。

沒有真正需要使用 while 循環，其他方法可能更有效，例如使用列表或數組。 但是，對於我的回答，我尊重您代碼的原始結構。

Answer 2

months_invested由行設置months_invested = float() ，它被初始化為零。 這意味着 while 循環永遠不會運行。 你想要months_invested = years_investment * 12 。

值得注意的是，這仍然不會如你所願，但我不想為你提供完整的答案：與問題作斗爭是學習的重要組成部分。

Answer 3

你在這里有幾件事。

1. while 循環將在滿足條件時進入，並且似乎永遠不會在命中 while 循環之前從float()改變。
2. 縮進關閉， years_investment = 0之后的所有內容都不在main()函數中。 （這可能只是發布問題時的復制/粘貼問題。）
3. 當你進入 for 循環時，你最終會堅持下去，因為你實際上並沒有減少months_investment值。

我做了一些重構，讓你到達我認為你想去的地方。

def main():
    investment = float(input("How much would you like to invest? "))
    months_investment = float(int(input("How many years would you like to invest? ")) * 12)
    interest_rate = float(input("What is the interest rate? "))
    total_money = 0

    while months_investment > 0:
        total_money += investment * interest_rate
        print("You have earned ${:,.2f}".format(total_money))
        months_investment -= 1
    else: print("You've earned a total of ${:,.2f}".format(total_money))


main()