x = [4, 6, 2, 1, 7, 9]
x.sort()
print x # [1, 2, 4, 6, 7, 9]

x =[4, 6, 2, 1, 7, 9]
y = x[ : ]
y.sort()
print y #[1, 2, 4, 6, 7, 9]
print x #[4, 6, 2, 1, 7, 9]

x =[4, 6, 2, 1, 7, 9]
y = sorted(x)
print y #[1, 2, 4, 6, 7, 9]
print x #[4, 6, 2, 1, 7, 9]

print sorted('Python') #['P', 'h', 'n', 'o', 't', 'y']

def comp(x, y):
if x < y:
return 1
elif x > y:
return -1
else:
return 0

nums = [3, 2, 8 ,0 , 1]
nums.sort(comp)
print nums # 降序排序[8, 3, 2, 1, 0]
nums.sort(cmp) # 调用内建函数cmp ，升序排序
print nums # 降序排序[0, 1, 2, 3, 8]

x = ['mmm', 'mm', 'mm', 'm' ]
x.sort(key = len)
print x # ['m', 'mm', 'mm', 'mmm']

y = [3, 2, 8 ,0 , 1]
y.sort(reverse = True)
print y #[8, 3, 2, 1, 0]