我无法让函数返回全局变量

Question

追踪（最近一次通话）：   文件“C：\ Users \ Mitch \ Documents \ lab3.py”，第18行，in     主要（）   在主文件中输入文件“C：\ Users \ Mitch \ Documents \ lab3.py”，第15行     finddiscount（数量）   在finddiscount中输入文件“C：\ Users \ Mitch \ Documents \ lab3.py”，第2行     如果数量＆gt; = 1且数量＆lt; = 9： NameError：未定义全局名称“数量”

def finddiscount(discount):
    if quantity >= 1 and quantity <= 9:
        discount = "0%"
    elif quantity >= 10 and quantity <= 19:
        discount = "20%"
    elif quantity >= 20 and quantity <= 49:
        discount = "30%"
    elif quantity >= 50 and quantity <= 99:
        discount = "40%"
    elif quantity >= 100:
        discount = "50%"
    print (discount)    
def main():
    quantity = int(input("How many packages where purchased?"))
    finddiscount(quantity)
    price = float(input("How much is each item?"))
    return
main()

Answer 1

尝试

def finddiscount(quantity):   # not discount!