Python while循环

Question

我在python3中有这段代码，用于检查输入时的错误，但我需要确定输入是否为整数，如果不是，则打印错误消息。

有人能帮我找出while循环中的代码吗？谢谢

price = 110;

ttt = 1;

while price < 0 or price > 100:

    price = input('Please enter your marks for Maths:');
    ttt =ttt +1;
    if ttt >= 2:
        print( 'This is an invalid entry, Please enter a number between 0 and 100')

Answer 1

使用int()函数将其转换为整数。这将在无法执行转换时引发ValueError：

try:
    price = int(price)
except ValueError as e:
    print 'invalid entry:', e

Answer 2

您可能想要这样的代码，它既可以捕获价格是否为整数，也可以捕获价格是否在0到100之间，如果满足这些条件，则中断循环。

while True:
    price = raw_input('Please enter your marks for Maths:')
    try:
        price = int(price)
        if price < 0 or price > 100:
            raise ValueError
        break
    except ValueError:
        print "Please enter a whole number from 0 to 100"

print "The mark entered was", price

或者，由于您具有可管理的少量可能值，因此您还可以执行以下操作：

valid_marks = [str(n) for n in range(101)]
price = None
while price is None:
    price = raw_input('Please enter your marks for Maths:')
    if not price in valid_marks:
       price = None
       print "Please enter a whole number from 0 to 100"

Answer 3

首先，使用raw_input而不是input。

此外，将ttt检查放在输入之前，以便正确显示错误：

price = 110;
ttt = 1;
while price < 0 or price > 100:
    if ttt >= 2:
        print 'This is an invalid entry, Please enter a number between 0 and 100';
    price = raw_input('Please enter your marks for Maths:');
    ttt = ttt +1;