我想在另一个函数中使用一个函数的返回值，而无需再次运行该函数。 （Python）

Question

例如，现在每次我使用 cost = get_cost() 时，该函数都会通过并再次要求输入。有没有办法只保存返回值，所以我可以在另一个函数中使用该值？感谢大家的帮助。

def get_cost():

    cost = float(input('Please Enter the Cost of the Meal: '))

    while cost <= 0:
        print('The Cost Must Be Greater Than 0!')
        cost = float(input('Please Enter the Cost of the Meal: '))
    else:
        return cost

def compute_tip():

    cost = get_cost()

    finalTip = cost * 0.18
    return finalTip

def compute_tax():

    cost = get_cost()

    finalTax = cost * 0.0825
    return finalTax

def compute_grand_total():

    cost = get_cost()    
    finalTip = compute_tip()
    finalTax = compute_tax()

    grandTotal = cost + finalTip + finalTax
    return grandTotal

def display_total_cost():

    cost = get_cost()
    finalTip = compute_tip()
    finalTax = compute_tax()
    grandTotal = compute_grand_total()

    print('Cost\t$', format(cost, '.2f'))
    print('Tip\t$', format(finalTip, '.2f'))
    print('Tax\t$', format(finalTax, '.2f'))
    print('Total\t$', format(grandTotal, '.2f'))


def main():

    get_cost()

    compute_tip()

    compute_tax()

    compute_grand_total()

    display_total_cost()

main()

Answer 1

看起来你的主函数只需要包含一个函数调用

def main():
    display_total_cost()

因为display_total_cost() 会根据需要在内部调用所有其他函数。

然后您可以将cost 作为函数参数传递给需要它的其他函数，并从所有其他函数中删除get_cost 调用。这是您的脚本的更新版本：

def get_cost():

    cost = float(input('Please Enter the Cost of the Meal: '))

    while cost <= 0:
        print('The Cost Must Be Greater Than 0!')
        cost = float(input('Please Enter the Cost of the Meal: '))
    else:
        return cost

def compute_tip(cost):
    finalTip = cost * 0.18
    return finalTip

def compute_tax(cost):
    finalTax = cost * 0.0825
    return finalTax

def display_total_cost():

    cost = get_cost()
    finalTip = compute_tip(cost)
    finalTax = compute_tax(cost)
    grandTotal = cost + finalTip + finalTax

    print('Cost\t$', format(cost, '.2f'))
    print('Tip\t$', format(finalTip, '.2f'))
    print('Tax\t$', format(finalTax, '.2f'))
    print('Total\t$', format(grandTotal, '.2f'))


def main():
    display_total_cost()

# common practice is to include this line
if __name__ == "__main__":
    main()

Answer 2

一旦返回值，您必须保存该值，并将其传递给其他函数。像这样的：

def main():
    cost = get_cost()
    tip = compute_tip(cost)
    tax = compute_tax(cost)
    total = compute_grand_total(tip, tax)
    display_total_cost(total)

但您还必须重写函数以接受这些参数，例如：

def compute_tip(cost):
    finalTip = cost * 0.18
    return finalTip

Answer 3

添加参数，这样你就不需要一直调用相同的函数了。

    def get_cost():

    cost = float(input('Please Enter the Cost of the Meal: '))

    while cost <= 0:
        print('The Cost Must Be Greater Than 0!')
        cost = float(input('Please Enter the Cost of the Meal: '))
    else:
        return cost

def compute_tip(cost):

    finalTip = cost * 0.18
    return finalTip

def compute_tax(cost):

    finalTax = cost * 0.0825
    return finalTax

def compute_grand_total(cost, finalTip, finalTax):

    grandTotal = cost + finalTip + finalTax
    return grandTotal

def display_total_cost(cost):

    finalTip = compute_tip(cost)
    finalTax = compute_tax(cost)
    grandTotal = compute_grand_total(cost, finalTip, finalTax)

    print('Cost\t$', format(cost, '.2f'))
    print('Tip\t$', format(finalTip, '.2f'))
    print('Tax\t$', format(finalTax, '.2f'))
    print('Total\t$', format(grandTotal, '.2f'))

def main():

    cost = get_cost()

    display_total_cost(cost)

main()