Question

我认为if-elif-else语句有问题，因为它总是转到其他地方

#initialize total
total=0.0
#ask for inputs
budget=float(input("Plz Enter amount that you budgeted for a month: "))
expense=float(input("Plz Enter 1st expense - to quit enter 0: "))
while expense!=0:
# Add the expense to the accumulator.
    total += expense
    expense=float(input("Plz Enter a expense - to quit enter 0: "))
#display results
if total>budget:
        print("You are over-budget by",total-budget)
elif budget<total:
        print("You have",budget-total,"to spare")
else:
        print("Your budget is equal to expense")

Answer 1

if和elif都在做同样的事情

if total>budget:
    print("You are over-budget by",total-budget)
elif budget<total:
    print("You have",budget-total,"to spare")

应该是：

if total>budget:
    print("You are over-budget by",total-budget)
elif budget>total:
    print("You have",budget-total,"to spare")

但是，为了更清洁（你会发现错误更容易）：

if total>budget:
    print("You are over-budget by",total-budget)
elif total<budget:
    print("You have",budget-total,"to spare")

了解总计现在是如何对齐的？更容易看出操作员方向的差异。不需要思考。

Answer 2

我建议，当对同一组变量执行if / elif时，始终保持顺序相同，这样可以提高可读性，并且更适合错误检查。你的大脑会进行一次艰难的上下文切换，以便了解它们的顺序是否相同，但标志是相同的，这是非直观的。

你的if / elif / else应该如下：

if total > budget:
    print("You are over-budget by",total-budget)
elif total < budget:
    print("You have",budget-total,"to spare")
else:
    print("Your budget is equal to expense")

python if-elif-else总是去其他地方

2 个答案: