Python基础之循环语句用法示例【for、while循环】

#!/usr/bin/env python3
n = 100
sum = 0
counter = 1
while counter <= n:
　　sum = sum + counter
　　counter += 1
print("Sum of 1 until %d: %d" % (n,sum))

>>> languages = ["C", "C++", "Perl", "Python"]
>>> for x in languages:
 ... print x
 ...
C
C++
Perl Python
>>>

#!/usr/bin/env python3
edibles = ["ham", "spam","eggs","nuts"]
for food in edibles:
　　if food == "spam":
　　　　print("No more spam please!")
　　　　break
　　print("Great, delicious " + food)
else:
　　print("I am so glad: No spam!")
print("Finally, I finished stuffing myself")

>>> for i in range(5):
... print(i)
...
0
1
2
3
4

>>> for i in range(5,9) :
print(i)
5
6
7
8
>>>

>>> for i in range(0, 10, 3) :
print(i)
0
3
6
9
>>>
负数：
>>> for i in range(-10, -100, -30) :
print(i)
-10
-40
-70
>>>

>>> 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

>>> list(range(5))
[0, 1, 2, 3, 4]
>>>

>>> for n in range(2, 10):
...　　 for x in range(2, n):
... 　　　　if n % x == 0:
... 　　　　　　print(n, 'equals', x, '*', n//x)
... 　　　　　　break
...　　 else:
... 　　# 循环中没有找到元素
... 　　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

>>> while True:
... pass # 等待键盘中断 (Ctrl+C)

>>> class MyEmptyClass:
... pass