Python中的流程控制详解

In [56]: while x < 10 :
 ...:  print(x)
 ...:  x, y = y, x+y
 ...:
0
1
1
2
3
5
8

> x = int(input("Please enter an integer: "))
Please enter an integer: 42
> if x < 0:
...  x = 0
...  print('Negative changed to zero')
... elif x == 0:
...  print('Zero')
... elif x == 1:
...  print('Single')
... else:
...  print('More')
...
More

In [57]: ages = [ 10, 14, 18, 20 ,25]

In [58]: for age in ages:
 ...:  print(age)
 ...:
10
14
18
20
25

In [59]: for age in ages.copy():
 ...:  print(age)
 ...:
10
14
18
20
25

In [61]: for age in range(5):
 ...:  print(age)
 ...:
0
1
2
3
4

In [62]: for age in range(5, 10 , 2):
 ...:  print(age)
 ...:
5
7
9

> a = ['Mary', 'had', 'a', 'little', 'lamb']
> for i in range(len(a)):
...  print(i, a[i])
...
0 Mary
1 had
2 a
3 little
4 lamb

In [64]: for n in range(2, 10):
 ...:  for x in range(2, n):
 ...:   if n % x == 0:
 ...:    print(n, 'equals', x, '*', n//x)
 ...:    break
 ...:  else:
 ...:   print(n, 'is a prime number')
 ...:
2 is a prime number
3 is a prime number
4 equals 2 * 2
5 is a prime number
6 equals 2 * 3
7 is a prime number
8 equals 2 * 4
9 equals 3 * 3

In [68]: for n in range(2, 10):
 ...:  for x in range(2, n):
 ...:   if n % x == 0:
 ...:    print(n, 'equals', x, '*', n//x)
 ...:    continue
 ...:  else:
 ...:   print(n, 'is a prime number')
 ...:
2 is a prime number
3 is a prime number
4 equals 2 * 2
4 is a prime number
5 is a prime number
6 equals 2 * 3
6 equals 3 * 2
6 is a prime number
7 is a prime number
8 equals 2 * 4
8 equals 4 * 2
8 is a prime number
9 equals 3 * 3
9 is a prime number

> while True:
...  pass # Busy-wait for keyboard interrupt (Ctrl+C)
...

> class MyEmptyClass:
...  pass
...

> def initlog(*args):
...  pass # Remember to implement this!
...