`TypeError：一元+的错误操作数类型：'str'`答案

【问题标题】：`TypeError: bad operand type for unary +: 'str'``TypeError：一元+的错误操作数类型：'str'`
【发布时间】：2021-01-15 10:10:27
【问题描述】：

我的程序运行了，但是在我输入答案后，我不断收到一个错误提示

"TypeError: 一元+的错误操作数类型: 'str'

def calculateCaloriesFromFat(fatGrams):
    caloriesFromFat = fatGrams * 9
    return caloriesFromFat


def calculateCaloriesFromCarbs(carbGrams):
    caloriesFromCarbs = carbGrams * 4
    return caloriesFromCarbs
  

def main():
    userFatGrams = float(input("How many Fat Grams?"))
    userCarbGrams = float(input("How many Carb Grams?"))

    caloriesFromFat = calculateCaloriesFromFat(userFatGrams)
    caloriesFromCarbs = calculateCaloriesFromCarbs(userCarbGrams)

    print("calories from fat", + format(caloriesFromFat, "f"),
          "calories from carbs", + format(caloriesFromCarbs, "f"))


main()

【问题讨论】：

标签： python typeerror

【解决方案1】：

这里不需要+ 标志：

print("calories from fat", format(caloriesFromFat, "f"),
      "calories from carbs", format(caloriesFromCarbs, "f"))

【讨论】：

【解决方案2】：

以下应该有效：

def calculateCaloriesFromFat(fatGrams):
    caloriesFromFat = fatGrams * 9
    return caloriesFromFat


def calculateCaloriesFromCarbs(carbGrams):
    caloriesFromCarbs = carbGrams * 4
    return caloriesFromCarbs

def main():
    userFatGrams = float(input("How many Fat Grams?"))
    userCarbGrams = float(input("How many Carb Grams?"))

    caloriesFromFat = calculateCaloriesFromFat(userFatGrams)
    caloriesFromCarbs = calculateCaloriesFromCarbs(userCarbGrams)

    print("calories from fat " + format(caloriesFromFat, "f") + "calories from carbs " + format(caloriesFromCarbs, "f"))

main()

但是，请考虑将format(caloriesFromFat, "f") 更改为：

print("calories from fat " + str(caloriesFromFat) + " calories from carbs " + str(caloriesFromCarbs))

通过这样做，您将消除不需要的任何多余的零。

【讨论】：