python - 修复 UnboundLocalError

Question

def main():
    cash = float(input("How much money: "))
    coins = 0

def changeCounter(n):
    while True:
        if cash - n > 0:
            cash -= n
            coins += 1
        else:
            break
    return

main()
changeCounter(0.25)

当我运行此代码时，出现错误

UnboundLocalError: local variable 'cash' referenced before assignment

我该如何解决这个问题？

Answer 1

问题在于变量 cash和coins只生活在函数的“范围”内 main ，即在 changeCounter 中不可见。尝试:

def main():
    cash = float(input("How much money: "))
    coins = 0
    return cash, coins

def changeCounter(n, cash, coins):
    while True:
        if cash - n > 0:
            cash -= n
            coins += 1
        else:
            break
    # return
    return coins # presumably

cash, coins = main()
changeCounter(0.25, cash, coins)