标签：元组 迭代 class 函数 pid bsp 异常 字符 cep
iter()函数和next()函数
使用iter(序列)函数可以获得一个迭代器，使用next(迭代器)函数可以获得迭代器中的下一条数据，例如；
l = [1,2,3] s = ‘hello world‘ t = (1,2,3,‘hello‘) it1 = iter(l) it2 = iter(s) it3 = iter(t) print(next(it1)) # 1 print(next(it2)) # h print(next(it3)) # 1
StopIteration 异常
当迭代器中没有数据时，会抛出一个StopIteration 异常，利用该异常判断迭代结束，例如：
l = [1,2,3]
it = iter(l)
while True:
try:
x = next(it)
print(x)
except StopIteration as si:
# print(‘end‘)
break
# 1 2 3
迭代字符串、列表、元组和字典
l = [1,2,3]
s = ‘hello world‘
t = (1,2,3,‘hello‘)
it1 = iter(l)
it2 = iter(s)
it3 = iter(t)
print(next(it1)) # 1
print(next(it2)) # h
print(next(it3)) # 1
# 字典
d = {‘pid‘:‘123‘,‘name‘:‘tom‘,‘age‘:‘20‘}
it = iter(d) # keys
for k in it:
v = d[k]
print(k,v ,end=‘ ‘)
使用for/while循环迭代
l = [1,2,3]
it = iter(l)
for x in it:
print(x)
# 1 2 3
it = iter(l)
while True:
try:
x = next(it)
print(x)
except StopIteration as si:
break
# 1 2 3
标签：元组 迭代 class 函数 pid bsp 异常 字符 cep
原文地址：http://www.cnblogs.com/lcgsmile/p/7652048.html
