课程名称:全面系统Python3.8入门+进阶(程序员必备第二语言)
课程章节:5-8 不只是数字才能做比较运算
5-9 逻辑运算符
课程内容:
今天学习的内容包括:
不只是数字才能做比较运算
逻辑运算符
课程收获:
不只是数字才能做比较运算
b = 1
b+=b>=1
print(b) -------- 2
print(b>=1) ----True # 可以转化成 b+=True 或者 b = b + True
int(True) ----- 1
b = b + 1 ------- 2 # 可以证明这个算术题是等于2
<article data-content="[{"type":"block","id":"KwUF-1660643434730","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"63ds-1660643434729","leaves":[{"text":"" a'=""> 'b' --- False #比较2个字母的阿斯克码","marks":[]}]}],"state":{}},{"type":"block","id":"OQCi-1660643477620","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"WZJz-1660643477619","leaves":[{"text":"ord('a') ---97","marks":[]}]}],"state":{}},{"type":"block","id":"qqa8-1660643490006","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"LjI9-1660643490005","leaves":[{"text":"ord('b') ---98","marks":[]}]}],"state":{}},{"type":"block","id":"sawj-1660643498704","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"510N-1660643498703","leaves":[{"text":"------------------------------------------------------------------------------------------------------","marks":[]}]}],"state":{}},{"type":"block","id":"cife-1660643519399","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"kErG-1660643519398","leaves":[{"text":"'abc' < 'abd' -------True # 先比较 a和a ,在比较b和b,最后比较c=99和d=100。 所以最后'abc' < 'abd'是True。","marks":[]}]}],"state":{}},{"type":"block","id":"AJwg-1660643541037","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"F5Bq-1660643541035","leaves":[{"text":"ord('abc') ----- # 报错","marks":[{"type":"color","value":"#F33232"}]}]}],"state":{}},{"type":"block","id":"bGlQ-1660643555335","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"Mu6L-1660643555334","leaves":[{"text":"当一个字符串里面有多个元素的时候,他的比较规则----解析规则:他会吧字符串里面每个字符单独拿出来做比较。","marks":[]}]}],"state":{}},{"type":"block","id":"ekLD-1660643601256","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"1GaW-1660643601255","leaves":[{"text":"------------------------------------------------------------------------------------------------------","marks":[]}]}],"state":{}},{"type":"block","id":"Saga-1660643785229","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"OIEe-1660643785228","leaves":[{"text":"列表: 关系运算","marks":[]}]}],"state":{}},{"type":"block","id":"0UlJ-1660643817388","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"5iNK-1660643817387","leaves":[{"text":"[1,2,3] < [2,3,4] ----- True # 先比较2个列表第一个元素,就能得到结果。","marks":[]}]}],"state":{}},{"type":"block","id":"ujOI-1660643876909","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"zD2m-1660643876908","leaves":[{"text":"元组:","marks":[]}]}],"state":{}},{"type":"block","id":"onZh-1660643883954","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"jS1d-1660643883953","leaves":[{"text":"(1,2,3) < (1,3,2) -----Ture #第一个元素相等, 第二个元素2<3.所以能得出Ture","marks":[]}]}],"state":{}},{"type":"block","id":"vEGI-1660644028939","name":"paragraph","data":{"version":1},"nodes":[{"type":"text","id":"JjMQ-1660644028938","leaves":[{"text":"","marks":[]}]}],"state":{}}]'>
'a' > 'b' --- False #比较2个字母的阿斯克码
ord('a') ---97
ord('b') ---98
------------------------------------------------------------------------------------------------------
'abc' < 'abd' -------True # 先比较 a和a ,在比较b和b,最后比较c=99和d=100。 所以最后'abc' < 'abd'是True。
ord('abc') ----- # 报错
当一个字符串里面有多个元素的时候,他的比较规则----解析规则:他会吧字符串里面每个字符单独拿出来做比较。
------------------------------------------------------------------------------------------------------
列表: 关系运算
[1,2,3] < [2,3,4] ----- True # 先比较2个列表第一个元素,就能得到结果。
元组:
(1,2,3) < (1,3,2) -----Ture #第一个元素相等, 第二个元素2<3.所以能得出Ture
5-9逻辑运算符
and or not
逻辑运算符主要是用来操作布尔类型的。返回结果也是布尔类型的。
and (且),与 操作的2额类型都是真才,返回True
True and True ----True
True and False ----- False
or (或)
True or False ------ True
False or False ------ False
not 非 ; 他只操作一个变量
not False ----- True
not True ----- False
not not True ---- True # not True =Fasle ,not False=True
1 and 1 ---1
'a' and 'b' ------'b'
'a' or 'b' ----- 'a'
not 'a'-----False
上面数字和字母和布尔类型有转换关系:1 = True; a = True b = True
int float 0表示False,非0的时候将被任务是True
not 0.1 --------False
字符串【空字符串】将被认为False,负责被认为True。
not '' ------True
not ‘0’ ------ False #字符串,有值会被认为是True,not后未False
列表:空列表将被认为是False,非空的列表将被认为是True
not [] -----True
not[1.2] ---- False
tuple(元组) set(集合) dict(字典):他们同样遵循和列表一样的逻辑。
[1] or [ ] ------[1] #他将得到第一个元素。
[ ] or [1] -----[1] #不要关心or运算返回的是第一个元素还是第二个元素。要关心这个运算的结果到底代表着是Ture还是false,这是我们关注的重点。
'a' and 'b' -----'b'
' ' and 'b' -----' '
not一定范围True和False。
1 and 0 ----0
0 and 1 ----0
#返回规律,当计算机读到第一个1的时候不能返回结果。他要比较2个数字。and是比较2个数字,他读到1 and时候不能判断结果。
1 and 2 -------2
#