Question

我想创建一个循环，运行n次，其中：

'n'可以自由更改
'n'在没有传递值时应该有一个默认值
'n'应该在需要时永远运行

我目前的代码如下：

n = raw_input('number of runs: ')       # Get user input for 'n'
if n == '':                             # Empty input -> run the loop 1000 times (condition 2)
    a = 1000                            # Default value
elif n == 'oo':                         # Run the loop forever
    a = 9000                            # This value isn't important could be 1 aswell see while statement
else:
    a = n                               # Run the loop for the value provided in raw_input
i = 1
while i <= int(a):
    if n == 'oo': 
        a += 1                          # If n=∞, increment 'a' after each iteration so the loop never stops
    print i                             # Print 'i' to see if everything works like expected
    i += 1

如何让这段代码更优雅（我觉得有更简单的方法）？如何在不使用键盘中断的情况下使循环（对于n ='oo'）停止？

Answer 1

使用for - 循环和不同的迭代：

from itertools import count

n = raw_input('number of runs: ')
if n == '':     #empty input-> run the loop 1000 times
    counter = xrange(1, 1001)
elif n == 'oo': #run the loop forever
    counter = count(1)
else:
    counter = xrange(1, int(n)+1)   #otherwise run the loop for the value provided above
for i in counter:
    print i    #print i to see if everything works like expected

Answer 2

a = raw_input('Enter value for a: ')

try:
   a = int(a)
except:
   if a != 'oo':
       a = 10000

if a == 'oo':
   while True:
       print "infinite"
       pass
else:
   while a != 0:
       # do something
       print a
       a = a - 1

Python循环使用默认值，否则无限

2 个答案: