將float變量轉換為字符串

Question

我正在嘗試轉換其值更改的變量，但是該值通常為小數點后一位，例如0.5。 我正在嘗試將此變量更改為0.50。 我正在使用此代碼，但是在運行程序時顯示TypeError: Can't convert 'float' object to str implicitly

這是我的代碼：

while topup == 2:
    credit = credit + 0.5
    credit = str(credit)
    credit = '%.2f' % credit
    print("You now have this much credit £", credit)
    vending(credit)

Answer 1

while topup == 2:
    credit = float(credit) + 0.5
    credit = '%.2f' % credit
    print("You now have this much credit £", credit)
    vending(credit)

問題是您不能浮點格式設置字符串

"%0.2f"%"3.45"  # raises error

相反，它期望一個數字

"%0.2f"%3.45   # 0k
"%0.2f"%5   # also ok

因此，當您調用str(credit)它會破壞下面的格式字符串（順便說一句，也會將功勞轉換回字符串）

順便說一句，您應該只在打印時才這樣做

credit = 1234.3
print("You Have : £%0.2f"%credit)

通常，您希望您的信用是數字類型，以便您可以用它進行數學運算