import time#导入时间模块

time.sleep(5)#输入间隔时间5秒

def p_bz():#使用函数   生产包子

    for i in range(100):

        yield "包子%s"%(i+1)

x=p_bz()

print(x.__next__())

print(x.__next__())

print(x.__next__())

a=sum([i for i in range(10000000)])#内存占用大，容易卡死

print(a)

b=sum(i for i in range(10000000))#几乎不占内存

print(b)

# g=open('test2','r+',encoding='utf-8')

# g.close()

def gp():

    with open("test2",'r',encoding='utf-8') as f:

        for i in f:

            yield i

h=gp()

s1=eval(h.__next__())#转化为字典

print(type(s1))

print(s1['population'])

allp=sum(eval(i)['population'] for i in h)

print('总人口sum方法：：',allp)

""""""""""""""

res = 0

for i in h:

    s2=eval(i)

    print(s2['name'])

    res+=s2['population']

print ('总人口for方法：',res)