第 5讲python 中的循环语句

5: #5不大于5","marks":[]}]}],"state":{}},{"type":"block","id":"nltg-1661596597430","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"pvvJ-1661596597265","leaves":[{"text":"print('美女')","marks":[]}]}],"state":{}},{"type":"block","id":"aURb-1661596597431","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"BZ4w-1661596597267","leaves":[{"text":"else: #上面不成立走这里","marks":[]}]}],"state":{}},{"type":"block","id":"TLJ0-1661596597432","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"DShG-1661596597269","leaves":[{"text":"print('帅哥')","marks":[]}]}],"state":{}},{"type":"block","id":"7Tdj-1661596597433","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"MGlE-1661596597271","leaves":[{"text":"2）if 判断语句多分支","marks":[]}]}],"state":{}},{"type":"block","id":"yXlJ-1661596597434","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"2HZB-1661596597273","leaves":[{"text":"name = input('请输入您的用户名：')","marks":[]}]}],"state":{}},{"type":"block","id":"zUSi-1661596597435","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"Mptu-1661596597275","leaves":[{"text":"if name =='admin':","marks":[]}]}],"state":{}},{"type":"block","id":"VweS-1661596597436","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"zB2W-1661596597277","leaves":[{"text":"print('管理员')","marks":[]}]}],"state":{}},{"type":"block","id":"rmUu-1661596597437","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"3zd2-1661596597279","leaves":[{"text":"elif name =='dcs':","marks":[]}]}],"state":{}},{"type":"block","id":"fY64-1661596597438","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"6Gqb-1661596597281","leaves":[{"text":"print('number one')","marks":[]}]}],"state":{}},{"type":"block","id":"80nG-1661596597439","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"HeLX-1661596597283","leaves":[{"text":"elif name =='xiaoduan':","marks":[]}]}],"state":{}},{"type":"block","id":"a1Jy-1661596597440","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"5pgK-1661596597285","leaves":[{"text":"print('穷人')","marks":[]}]}],"state":{}},{"type":"block","id":"NLwo-1661596597441","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"goWq-1661596597287","leaves":[{"text":"else:","marks":[]}]}],"state":{}},{"type":"block","id":"UJyI-1661596597442","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"Ve6L-1661596597290","leaves":[{"text":"print('普通用户')","marks":[]}]}],"state":{}},{"type":"block","id":"9GWb-1661596597443","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"ntPC-1661596597292","leaves":[{"text":"3)if条件判断语句中的三目运算==>适用于单分支","marks":[]}]}],"state":{}},{"type":"block","id":"impq-1661596597444","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"nI0Z-1661596597294","leaves":[{"text":"name = input('请输入您的用户名：')","marks":[]}]}],"state":{}},{"type":"block","id":"lfY8-1661596597445","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"LIPC-1661596597296","leaves":[{"text":"print('南京') if name =='xiaoduan' else print('深圳')","marks":[]}]}],"state":{}},{"type":"block","id":"MvtZ-1661596597446","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"Y4jq-1661596597298","leaves":[{"text":"上面改成不是三目运算","marks":[]}]}],"state":{}},{"type":"block","id":"JBpI-1661596597447","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"nPIQ-1661596597300","leaves":[{"text":"name = input('请输入您的用户名：')","marks":[]}]}],"state":{}},{"type":"block","id":"Hir5-1661596597448","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"1qtQ-1661596597302","leaves":[{"text":"if name =='xiaoduan':","marks":[]}]}],"state":{}},{"type":"block","id":"w0c2-1661596597449","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"W2Sj-1661596597304","leaves":[{"text":"print('南京')","marks":[]}]}],"state":{}},{"type":"block","id":"6JmS-1661596597450","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"rn45-1661596597306","leaves":[{"text":"else:","marks":[]}]}],"state":{}},{"type":"block","id":"rFbd-1661596597451","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"3Rdn-1661596597308","leaves":[{"text":"print('深圳')","marks":[]}]}],"state":{}},{"type":"block","id":"e3yV-1661596597452","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"TlXN-1661596597310","leaves":[{"text":"dict1 = {'name':'xiaoduan','age':18}","marks":[]}]}],"state":{}},{"type":"block","id":"IuoY-1661596597453","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"WdvN-1661596597312","leaves":[{"text":"if dict1.","marks":[]},{"text":"contains","marks":[{"type":"bold"}]},{"text":"('class') is True:","marks":[]}]}],"state":{}},{"type":"block","id":"xsyD-1661596597454","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"r50l-1661596597314","leaves":[{"text":"print(dict1)","marks":[]}]}],"state":{}},{"type":"block","id":"WC01-1661596597455","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"IYhX-1661596597316","leaves":[{"text":"else:","marks":[]}]}],"state":{}},{"type":"block","id":"K9J6-1661596597456","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"RUZy-1661596597318","leaves":[{"text":"dict1['class'] = 1833","marks":[]}]}],"state":{}},{"type":"block","id":"5BnU-1661596597457","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"Rzng-1661596597320","leaves":[{"text":"dict1.setdefault('class',1833)","marks":[]}]}],"state":{}},{"type":"block","id":"dhfV-1661596597458","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"xt4u-1661596597322","leaves":[{"text":"print(dict1) #{'name': 'xiaoduan', 'age': 18, 'class': 1833}","marks":[]}]}],"state":{}},{"type":"block","id":"i15X-1661596597459","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"AyU8-1661596597324","leaves":[{"text":"作业：上面的转为为三目运算","marks":[]}]}],"state":{}},{"type":"block","id":"fak1-1661596597460","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"x1R0-1661596597326","leaves":[{"text":"dict1 = {'name':'xiaoduan','age':18}","marks":[]}]}],"state":{}},{"type":"block","id":"ZbcK-1661596597461","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"xmIw-1661596597328","leaves":[{"text":"print(dict1) if dict1.","marks":[]},{"text":"contains","marks":[{"type":"bold"}]},{"text":"('class') is True else dict1.setdefault('class',1833) and print(dict1)","marks":[]}]}],"state":{}},{"type":"block","id":"MBFj-1661596597462","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"0L27-1661596597330","leaves":[{"text":"4)if 判断语句之嵌套","marks":[]}]}],"state":{}},{"type":"block","id":"uEzw-1661596597463","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"uV9J-1661596597332","leaves":[{"text":"if 判断条件1：","marks":[]}]}],"state":{}},{"type":"block","id":"vuaN-1661596597464","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":&quot

M8M-1661596597334","leaves":[{"text":"语句块1","marks":[]}]}],"state":{}},{"type":"block","id":"BFdX-1661596597465","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"34TS-1661596597336","leaves":[{"text":"if 判断条件2：","marks":[]}]}],"state":{}},{"type":"block","id":"yuDg-1661596597466","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"9xTF-1661596597338","leaves":[{"text":"语句块2","marks":[]}]}],"state":{}},{"type":"block","id":"vpMc-1661596597467","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"sw0Y-1661596597340","leaves":[{"text":"else：","marks":[]}]}],"state":{}},{"type":"block","id":"GMFu-1661596597468","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"HIBU-1661596597342","leaves":[{"text":"语句块3","marks":[]}]}],"state":{}},{"type":"block","id":"31Ry-1661596597469","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"CiHm-1661596597344","leaves":[{"text":"else:","marks":[]}]}],"state":{}},{"type":"block","id":&quot

2uN-1661596597470","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"B3s6-1661596597346","leaves":[{"text":"语句块4","marks":[]}]}],"state":{}},{"type":"block","id":"5ULP-1661596597471","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"EvsO-1661596597348","leaves":[{"text":"登录功能实战练习：","marks":[]}]}],"state":{}},{"type":"block","id":"YYf5-1661596597472","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"cWYk-1661596597350","leaves":[{"text":"通过输入函数输入用户名、先判断用户名是否正确、用户名正确则进行密码的判断如果用","marks":[]}]}],"state":{}},{"type":"block","id":"cQdI-1661596597473","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"y4E9-1661596597352","leaves":[{"text":"户名错误则提示：用户错误、请重新输入、密码错误则提示：您输入的密码有误、","marks":[]}]}],"state":{}},{"type":"block","id":"mp1S-1661596597474","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"GyTL-1661596597354","leaves":[{"text":"请重新输入密码输入正确则登录成功","marks":[]}]}],"state":{}},{"type":"block","id":"80sQ-1661596597475","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"5RxJ-1661596597356","leaves":[{"text":"用户名：username admin","marks":[]}]}],"state":{}},{"type":"block","id":"yJZK-1661596597476","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"v994-1661596597359","leaves":[{"text":"密码： pwd 123456","marks":[]}]}],"state":{}},{"type":"block","id":"ON1s-1661596597477","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":&quot

im4-1661596597361","leaves":[{"text":"username = input('请输入您的用户名：')","marks":[]}]}],"state":{}},{"type":"block","id":"6KxU-1661596597478","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"j84t-1661596597363","leaves":[{"text":"if username =='admin':","marks":[]}]}],"state":{}},{"type":"block","id":"M0Ps-1661596597479","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"ILZk-1661596597365","leaves":[{"text":"pwd = input('请输入您的密码：')","marks":[]}]}],"state":{}},{"type":"block","id":"22K8-1661596597480","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"MUlW-1661596597367","leaves":[{"text":"if pwd =='123456':","marks":[]}]}],"state":{}},{"type":"block","id":"gzaW-1661596597481","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"qV0H-1661596597369","leaves":[{"text":"print('登录成功')","marks":[]}]}],"state":{}},{"type":"block","id":"0Ex0-1661596597482","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"Tar2-1661596597371","leaves":[{"text":"else:","marks":[]}]}],"state":{}},{"type":"block","id":"41u1-1661596597483","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"CMnD-1661596597373","leaves":[{"text":"print('您输入的密码有误、请重新输入密码')","marks":[]}]}],"state":{}},{"type":"block","id":"3j1X-1661596597484","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"LG7B-1661596597375","leaves":[{"text":"else:","marks":[]}]}],"state":{}},{"type":"block","id":"AK1T-1661596597485","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"87Xv-1661596597377","leaves":[{"text":"print('用户错误、请重新输入')","marks":[]}]}],"state":{}},{"type":"block","id":"C2k3-1661596597486","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"5qTC-1661596597379","leaves":[{"text":"dict1 = {'user':'admin','pwd':'123456'}","marks":[]}]}],"state":{}},{"type":"block","id":"LX3K-1661596597487","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"uydn-1661596597381","leaves":[{"text":"user = input('请输入您的用户名：')","marks":[]}]}],"state":{}},{"type":"block","id":"acLJ-1661596597488","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"QR8y-1661596597383","leaves":[{"text":"if user ==dict1['user']:","marks":[]}]}],"state":{}},{"type":"block","id":"siD9-1661596597489","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"F39r-1661596597385","leaves":[{"text":"pwd = input('请输入您的密码：')","marks":[]}]}],"state":{}},{"type":"block","id":"SnRg-1661596597490","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"RyBm-1661596597387","leaves":[{"text":"if pwd ==dict1['pwd']:","marks":[]}]}],"state":{}},{"type":"block","id":"KjKS-1661596597491","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"WvOC-1661596597389","leaves":[{"text":"print('登录成功')","marks":[]}]}],"state":{}},{"type":"block","id":"I2if-1661596597492","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"AaM0-1661596597391","leaves":[{"text":"else:","marks":[]}]}],"state":{}},{"type":"block","id":"UEfA-1661596597493","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"21XX-1661596597393","leaves":[{"text":"print('您输入的密码有误、请重新输入密码')","marks":[]}]}],"state":{}},{"type":"block","id":"BxZQ-1661596597494","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"kiNb-1661596597395","leaves":[{"text":"else:","marks":[]}]}],"state":{}},{"type":"block","id":"jtN3-1661596597495","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"QBSo-1661596597397","leaves":[{"text":"print('用户错误、请重新输入')","marks":[]}]}],"state":{}},{"type":"block","id":"NvXD-1661596597496","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"fh6F-1661596597399","leaves":[{"text":"2、while循环语句","marks":[]}]}],"state":{}},{"type":"block","id":"9bqP-1661596597497","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"JOj1-1661596597401","leaves":[{"text":"while 条件表达式：循环体语句 while什么时候进入循环？","marks":[]}]}],"state":{}},{"type":"block","id":"sa12-1661596597498","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"MYEQ-1661596597403","leaves":[{"text":"当循环条件成立时，进入循环","marks":[]}]}],"state":{}},{"type":"block","id":"ANdE-1661596597499","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"YgNo-1661596597405","leaves":[{"text":"while什么时候退出循环？","marks":[]}]}],"state":{}},{"type":"block","id":"Dh0v-1661596597500","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"ReP4-1661596597407","leaves":[{"text":"当循环条件不成立时，退出循环注意：在写while循环语句时一定要让循环条件发生变化，","marks":[]}]}],"state":{}},{"type":"block","id":"aJC0-1661596597501","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"AOBl-1661596597409","leaves":[{"text":"否认很容易陷入死循环中","marks":[]}]}],"state":{}},{"type":"block","id":"1mFs-1661596597412","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"ZCVK-1661596597411","leaves":[{"text":"num = 1","marks":[]}]}],"state":{}},{"type":"block","id":"qhfO-1661596597414","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"Aok4-1661596597413","leaves":[{"text":"while num <=5:","marks":[]}]}],"state":{}},{"type":"block","id":"YRRU-1661596597416","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":&quot

Sya-1661596597415","leaves":[{"text":"print('这是第%d的次循环'%num)","marks":[]}]}],"state":{}},{"type":"block","id":"gYoO-1661596597419","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"BOHv-1661596597418","leaves":[{"text":"num +=1 #每循环一次加1  跳出循环等同于 num = num +1","marks":[]}]}],"state":{}},{"type":"block","id":"R5sU-1661596594593","name":"paragraph","data":{},"nodes":[{"type":"text","id":"DRz1-1661596594590","leaves":[{"text":"#例子2：根据while循环求出1-100 的和","marks":[]}]}],"state":{}},{"type":"block","id":"XlSv-1661596421527","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"AdCB-1661596421320","leaves":[{"text":"sum = 0    #求和变量","marks":[]}]}],"state":{}},{"type":"block","id":"GpjA-1661596421528","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"YHei-1661596421322","leaves":[{"text":"i = 1    #循环变量","marks":[]}]}],"state":{}},{"type":"block","id":"l5pB-1661596421529","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"8Xtl-1661596421324","leaves":[{"text":"while i <=100:","marks":[]}]}],"state":{}},{"type":"block","id":"d94o-1661596421530","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"jwYU-1661596421326","leaves":[{"text":"sum = sum +i    #每循环一次相加 i = 1 sum = 1 i = 2  sum = 3","marks":[]}]}],"state":{}},{"type":"block","id":"32AG-1661596421531","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"YLug-1661596421328","leaves":[{"text":"i = i+1       #i+=1 满足条件跳出循环当循环到100 i= 100==》 i= 101","marks":[]}]}],"state":{}},{"type":"block","id":"moLe-1661596421532","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"1VIq-1661596421330","leaves":[{"text":"#print(sum)    #打印每次循环的和","marks":[]}]}],"state":{}},{"type":"block","id":"oGP3-1661596421533","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"QUix-1661596421332","leaves":[{"text":"print(sum)          #5050 打印出最终的和","marks":[]}]}],"state":{}},{"type":"block","id":"uxxF-1661596421534","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"hqcY-1661596421334","leaves":[{"text":"例子3：根据while 循环求出1-100 奇数之和","marks":[]}]}],"state":{}},{"type":"block","id":"lGsf-1661596421535","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"v2Pg-1661596421336","leaves":[{"text":"j = 0    #求和变量","marks":[]}]}],"state":{}},{"type":"block","id":"uB2g-1661596421536","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"gPMZ-1661596421338","leaves":[{"text":"i= 1    #循环变量","marks":[]}]}],"state":{}},{"type":"block","id":"8cjX-1661596421537","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"EbJQ-1661596421340","leaves":[{"text":"while i i = 3  , 当i= 3  ==》i= 5","marks":[]}]}],"state":{}},{"type":"block","id":"C24M-1661596421540","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"xFrL-1661596421346","leaves":[{"text":"print(j)          #2500","marks":[]}]}],"state":{}},{"type":"block","id":"IDZb-1661596421349","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"qlK4-1661596421348","leaves":[{"text":"#例子4 ：根据while 循环求出1-100 偶数之和","marks":[]}]}],"state":{}},{"type":"block","id":"tIUR-1661596421541","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"bNQU-1661596421350","leaves":[{"text":"j = 0 #求和变量","marks":[]}]}],"state":{}},{"type":"block","id":"rNkO-1661596421542","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"gr5N-1661596421352","leaves":[{"text":"i = 2","marks":[]}]}],"state":{}},{"type":"block","id":"IEat-1661596421544","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"NfX0-1661596421354","leaves":[{"text":"while i <=100:","marks":[]}]}],"state":{}},{"type":"block","id":"eAe3-1661596421545","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"Wrpc-1661596421356","leaves":[{"text":"j = j+i","marks":[]}]}],"state":{}},{"type":"block","id":"HaTz-1661596421546","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"8Kck-1661596421358","leaves":[{"text":"i +=2","marks":[]}]}],"state":{}},{"type":"block","id":"5gK8-1661596421547","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"kaT2-1661596421360","leaves":[{"text":"print(j)       #2550","marks":[]}]}],"state":{}},{"type":"block","id":"TuFG-1661596421548","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"ylXC-1661596421362","leaves":[{"text":"例子5：根据while循环求1-100 之内偶数和奇数之差","marks":[]}]}],"state":{}},{"type":"block","id":"Sfkr-1661596421549","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"RLNX-1661596421364","leaves":[{"text":"even = 0    #偶数之和","marks":[]}]}],"state":{}},{"type":"block","id":"OQw5-1661596421550","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"TG4U-1661596421367","leaves":[{"text":"odd  = 0    #奇数之和","marks":[]}]}],"state":{}},{"type":"block","id":"O1Bh-1661596421551","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"f096-1661596421369","leaves":[{"text":"i = 1","marks":[]}]}],"state":{}},{"type":"block","id":"6dqj-1661596421552","name":"heading","data":{"version":1,"level":"h1"},"nodes":[{"type":"text","id":"93aA-1661596421371","leaves":[{"text":"while i第 5讲python  中的循环语句
1、if条件判断语句
1）if 条件判断语句单分支
name = input('请输入您的用户名：')
if name =='admin':
print('管理员')
else:
print('普通用户')

num = 5
if num >5:    #5不大于5
print('美女')
else:          #上面不成立走这里
print('帅哥')
2）if 判断语句多分支
name = input('请输入您的用户名：')
if name =='admin':
print('管理员')
elif name =='dcs':
print('number one')
elif name =='xiaoduan':
print('穷人')
else:
print('普通用户')
3)if条件判断语句中的三目运算==>适用于单分支
name = input('请输入您的用户名：')
print('南京') if name =='xiaoduan' else print('深圳')
上面改成不是三目运算
name = input('请输入您的用户名：')
if name =='xiaoduan':
print('南京')
else:
print('深圳')
dict1 = {'name':'xiaoduan','age':18}
if dict1.contains('class') is True:
print(dict1)
else:
dict1['class'] = 1833
dict1.setdefault('class',1833)
print(dict1)    #{'name': 'xiaoduan', 'age': 18, 'class': 1833}
作业：上面的转为为三目运算
dict1 = {'name':'xiaoduan','age':18}
print(dict1) if dict1.contains('class') is True else dict1.setdefault('class',1833) and print(dict1)
4)if 判断语句之嵌套
if 判断条件1：
语句块1
if 判断条件2：
语句块2
else：
语句块3
else:
语句块4
登录功能实战练习：
通过输入函数输入用户名、先判断用户名是否正确、用户名正确则进行密码的判断如果用
户名错误则提示：用户错误、请重新输入、密码错误则提示：您输入的密码有误、
请重新输入密码输入正确则登录成功
用户名：username admin
密码： pwd  123456
username = input('请输入您的用户名：')
if username =='admin':
pwd = input('请输入您的密码：')
if pwd =='123456':
print('登录成功')
else:
print('您输入的密码有误、请重新输入密码')
else:
print('用户错误、请重新输入')
dict1 = {'user':'admin','pwd':'123456'}
user = input('请输入您的用户名：')
if user ==dict1['user']:
pwd = input('请输入您的密码：')
if pwd ==dict1['pwd']:
print('登录成功')
else:
print('您输入的密码有误、请重新输入密码')
else:
print('用户错误、请重新输入')
2、while循环语句
while 条件表达式：循环体语句 while什么时候进入循环？
当循环条件成立时，进入循环
while什么时候退出循环？
当循环条件不成立时，退出循环注意：在写while循环语句时一定要让循环条件发生变化，
否认很容易陷入死循环中
num = 1
while num <=5:
print('这是第%d的次循环'%num)
num +=1 #每循环一次加1  跳出循环等同于 num = num +1
#例子2：根据while循环求出1-100 的和
sum = 0    #求和变量
i = 1    #循环变量
while i <=100:
sum = sum +i    #每循环一次相加 i = 1 sum = 1 i = 2  sum = 3
i = i+1       #i+=1 满足条件跳出循环当循环到100 i= 100==》 i= 101
#print(sum)    #打印每次循环的和
print(sum)          #5050 打印出最终的和
例子3：根据while 循环求出1-100 奇数之和
j = 0    #求和变量
i= 1    #循环变量
while i <=100:
j = j+i       #每循环一次相加 i = 1 sum = 1 i = 3 sum = 4
i = i+2       #控制取奇数当i = 1==>i = 3  , 当i= 3  ==》i= 5
print(j)          #2500
#例子4 ：根据while 循环求出1-100 偶数之和
j = 0 #求和变量
i = 2
while i <=100:
j = j+i
i +=2
print(j)       #2550
例子5：根据while循环求1-100 之内偶数和奇数之差
even = 0    #偶数之和
odd  = 0    #奇数之和
i = 1
while i<=100:
if i%2 ==0:    #判断是整除偶数
even = even +i
else:
odd = odd+i    #奇数
i = i+1
print(even-odd)    #50
3、for 循环语句
1）for 循环和range函数结合使用，for后面需要加一个冒号
for i in range(10):       #取不到10
# print(i)             #0-9 竖者打印
print(i,end="")       #0123456789

for i in range(0,10):    #这里取不到，能取到10
print(i)             ##0-9 竖者打印

for i in range(0,10,1):
print(i)             ##0-9 竖者打印  挨个取
for i in range(0,10,2):
print(i)             #0 2 4 6 8 隔一个取一个
for i in range(10,0):
print(i)                #打印为空
for i in range(10,0,-1):
print(i)                #10-1 0取不到，数字倒过来显示
2）for 循环语句示例
1、求1-100的和
j = 0    #定义一个求和变量
for i in range(1,101):
j = j+i
print(j)       #5050
2、求1-100 奇数之和
j = 0    #定义一个求和变量
for i in range(1,101,2):    #取1，3，5，7，9....
j = j+i
print(j)       #2500
3、求1-100偶数之和
j = 0    #定义一个求和变量
for i in range(2,101,2): #取 2,4,6,8,10....
j = j+i
print(j)       #2550
3）for 循环遍历作用字符串  列表  字典  元组  集合
1、遍历字符串
str1 = 'python'
for i in str1:
print(i)
2、遍历列表
list1 = [1,'dcs','test','中国']
for i in list1:
print(i)
3、遍历元组
tuple1 = (1,'dcs','xiaoduan')
for i in tuple1:
print(i)
4、遍历字典
dict1 = {'name':'xiaoduan','age':18}
for i in dict1:
print(i,dict1)          # i是键，dict1键取值
for j,k in dict1.items():    #打印出键和值
print(j,k)
5、遍历集合
t = 'python'
set1 = set(t)    #转化为集合
for i in set1:
print(i)
作业：用for 循环打印出duoceshi每个字符以及字符索引，并用格式化输出
str1 = 'duoceshi'
for i in str1:
print('%s对应的索引是%d'%(i,str1.index(i)))
4、continue语句用来告诉Python跳过当前循环的剩余语句，然后继续进行下一轮循环
for i in range(10):
if i ==6:          #当i = 6时
continue       #跳过i= 6这个循环，不会打印出来这个6
print(i,end="")    #012345789
5、break语句会立即退出循环，在其后边的循环代码不会被执行。
for i in range(10):
if i ==6:       #当i = 6时
break       #break当i = 6 时终止循环，只会打印到5
print(i,end="")          #012345