a =0
for b in range(101):
     a =a +b
print a

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

>>> sum = 0
>>> n= 99
>>> while n>0:
...     sum =sum + n
...     n = n-2
... 
>>> print sum
2500

n = 1
while n <= 100:
    if n > 10: # 当n = 11时，条件满足，执行break语句
        break # break语句会结束当前循环
    print(n)
    n = n + 1
print('END')

n = 0
while n < 10:
    n = n + 1
    if n % 2 == 0: # 如果n是偶数，执行continue语句
        continue # continue语句会直接继续下一轮循环，后续的print()语句不会执行
    print(n)