Ｐｙｔｈｏｎ之切片、迭代

#迭代
d = {'s':1,'b':2,'c':3};
#默认情况下,迭代的对象是ｋｅｙ，如果要迭代ｖａｌｕｅ，用for value in d.values(),如果要同时迭代key 和　value ，可以用for k,v in d.items()
print("迭代key")
for key in d:
    print(key)

print("迭代value")
for value in d.values():
    print(value)

print("迭代key 和　value")
for k,v in d.items():
    print(k,v)

###迭代字符窜
print("迭代字符串")
for ch in 'ABC':
    print(ch)

######如何判断对象是否可迭代＃＃＃＃＃＃＃＃
from collections import Iterable
abc = isinstance('abc',Iterable)
print("str 是否可迭代：")
print(abc)

my_list = isinstance([1,2,3],Iterable)
print("list 是否可迭代：")
print(my_list)

my_123 = isinstance(123,Iterable)
print("整数是否可迭代：")
print(my_123)

########利用　enumerate 函数将list 变成索引－元素对，实现下标循环＃＃＃＃＃＃
print("利用enumerate 实现索引和元素的同时迭代：")
for i,value in enumerate(['A','B','C']):
    print(i,value)

print("Python　中　for 循环中同时用两个变量：")
for x,y in [(1,1),(2,4),(3,9)]:
    print(x,y)

def findMinAndMax(L):
    #print(len(L))
    if len(L)<=0:
        return (None,None)
    else:
        Min = L[0]
        Max = L[0]
        for value in L[1:]:
            if value < Min:
                Min = value
            if value > Max:
                Max = value
        return(Min,Max)

# 测试
if findMinAndMax([]) != (None, None):
     print('测试失败!')
elif findMinAndMax([7]) != (7, 7):
    print('测试失败!')
elif findMinAndMax([7, 1]) != (1, 7):
    print('测试失败!')
elif findMinAndMax([7, 1, 3, 9, 5]) != (1, 9):
    print('测试失败!')
else:
    print('测试成功!')