无法在python中创建工作循环

Question

我对编程逻辑太陌生了，我不确定我是否能恰当地表达这一点。我正在使用Python2.7，并尝试编写一个脚本，该脚本将一直重复，直到输入0为止。我尝试了if、else和while语句，得出的结论是我对逻辑的了解不够，无法了解Python。例如…我太新了，所以初始化对我来说毫无意义。我几乎在收到的每个搜索结果中都看到过这个短语，但我不知道它是什么意思。我所在的类是逻辑类而不是Python类。我可以用伪代码写，但我真的很想看到一个工作模型。请帮忙。此脚本将运行并在输入零时退出，但不会再次提示行驶里程。你知道吗

#Cost of Trip Ch2 Q8
print "To Calculate the cost of your trip,"
print "enter the miles driven or zero to quit"
getMiles = float(input ('Enter Miles: '))
while getMiles == 0:
    print "END OF PROGRAM"
    exit
fuelEcon = getMiles / 20
fuelCost = float(input ('Enter Cost of Fuel: $'))
costOfTrip = getMiles * fuelCost
fuelIncrease = (fuelCost * .1) + fuelCost
futureTrip = getMiles * fuelIncrease
while costOfTrip == float:
    getMiles
print "Cost of Trip: $", costOfTrip
print "Cost of Trip With 10% Increase in Fuel Cost: $", futureTrip

我忘了提的是强制性的“项目结束”声明。我把你的答案和这个结合起来了。再次感谢大家。我可以不再把头撞在墙上了。你知道吗

#Cost of Trip Ch2 Q8
print "To Calculate the cost of your trip,"
print "enter the miles driven or enter zero to quit"
getMiles = float(raw_input ('Enter Miles: '))
while getMiles >= 0:
    if getMiles == 0:
        print "END OF PROGRAM"
        exit()
    fuelEcon = getMiles / 20
    fuelCost = float(input ('Enter Cost of Fuel: $'))
    costOfTrip = getMiles * fuelCost
    fuelIncrease = (fuelCost * .1) + fuelCost
    futureTrip = getMiles * fuelIncrease
    print "Cost of Trip: $", costOfTrip
    print "Cost of Trip With 10% Increase in Fuel Cost: $", futureTrip
    getMiles = float(raw_input ('Enter Miles: '))

Answer 1

你很接近，这是固定版本：

print "To Calculate the cost of your trip,"
print "enter the miles driven or zero to quit"
while True:
    getMiles = float(input ('Enter Miles: '))
    if getMiles == 0:
        print "END OF PROGRAM"
        exit()
    fuelEcon = getMiles / 20
    fuelCost = float(input ('Enter Cost of Fuel: $'))
    costOfTrip = getMiles * fuelCost
    fuelIncrease = (fuelCost * .1) + fuelCost
    futureTrip = getMiles * fuelIncrease
    print "Cost of Trip: $", costOfTrip
    print "Cost of Trip With 10% Increase in Fuel Cost: $", futureTrip

我在整个代码块周围添加了一个while True，这将导致问题被反复询问（永远），直到用户输入0英里。你知道吗

唯一需要修正的是exit是一个函数调用，所以它应该是exit()。你知道吗

Answer 2

我只是想说，作为一个风格的问题，即使你的新循环条件/逻辑可以很快整理起来阅读

print "To Calculate the cost of your trip,"
print "enter the miles driven or enter zero to quit"
getMiles = float(raw_input ('Enter Miles: '))
while getMiles != 0:
    fuelEcon = getMiles / 20
    fuelCost = float(input ('Enter Cost of Fuel: $'))
    costOfTrip = getMiles * fuelCost
    fuelIncrease = (fuelCost * .1) + fuelCost
    futureTrip = getMiles * fuelIncrease
    print "Cost of Trip: $", costOfTrip
    print "Cost of Trip With 10% Increase in Fuel Cost: $", futureTrip
    getMiles = float(raw_input ('Enter Miles: '))
print "END OF PROGRAM"
# should be no need for exit() unless code is included in a subroutine

Answer 3

Python实际上离伪代码不远，实际上这里的问题不是代码而是逻辑。你知道吗

要获得基本的“循环直到进入零”，可以使用以下逻辑：

miles = -1
while miles != 0:
    miles = float(raw_input ('Enter Miles: '))

至于你自己的代码，你似乎在用while，而你的意思是if 在第二种情况下，实际上只是命名一个变量（getMiles），它什么也不做

整个代码可以如下所示：

miles = float(raw_input ('Enter Miles: '))
while miles != 0:
    fuelEcon = miles / 20
    fuelCost = float(input ('Enter Cost of Fuel: $'))
    costOfTrip = miles * fuelCost
    fuelIncrease = (fuelCost * .1) + fuelCost
    futureTrip = miles * fuelIncrease

    print "Cost of Trip: $", costOfTrip
    print "Cost of Trip With 10% Increase in Fuel Cost: $", futureTrip

    miles = float(raw_input ('Enter Miles: '))

**不需要像其他人建议的那样使用“while true”，这从来都不是一件好事。你知道吗

更高级的版本是提取逻辑中可重复且独立于函数的部分

def trip_cost(miles):
    if(miles == 0):
        return False
    fuelEcon = miles / 20
    fuelCost = float(input ('Enter Cost of Fuel: $'))
    costOfTrip = miles * fuelCost
    fuelIncrease = (fuelCost * .1) + fuelCost
    futureTrip = miles * fuelIncrease
    print "Cost of Trip: $", costOfTrip
    print "Cost of Trip With 10% Increase in Fuel Cost: $", futureTrip

    return True

while trip_cost(float(raw_input ('Enter Miles: '))):
    pass

至于init是什么，这是一个更高级的面向对象的主题，您可能还不需要担心