day10，day11—基本数据类型语法

一、整形

1. base

#在16进制中的位置
num = "b"
v = int(num, base=16)
print(v)    #11

2. bit_length()

# 1  1
# 2  10
# 3  11
# 4  100
# 5  101
# 当前数字的二进制，至少用n位表示
age = 5
r = age.bit_length()
print(r)   #
age = 2
r = age.bit_length()
print(r)   #

二、字符串

需要记住六个基本魔法：join(), split(), find(), strip(), upper(), lower()

1. find

test = "alexalex"
v = test.find('lex',3)
print(v)
从第3个位置'x'查找'lex'

2. format

test = 'i am {name}, age {a}'
print(test)
v = test.format(name='alex',a=19)
print(v)

test = 'i am {0}, age {1}'
print(test)
v = test.format('alex',19)
print(v)

#格式化，传入的值 {"name": 'alex', "a": 19}
test = 'i am {name}, age {a}'
v1 = test.format(name='df',a=10)
v2 = test.format_map({"name": 'alex', "a": 19})
print(v1)
print(v2)

 

3. capitalize(), upper(), casefold(), lower()

test = "aLEx"
#首字母大写
v = test.capitalize()
print(v)
#所有字母大写
v2 = test.upper()
print(v2)

# 所有变小写，casefold更牛逼，很多未知的对相应变小写
v3 = test.casefold()
print(v3)
v4 = test.lower()
print(v4)

4. center

#设置宽度，并将内容居中
# 20 代指总长度
# *  空白未知填充，一个字符，可有可无
test = 'alex'
v = test.center(20,"中")
print(v)      # 中中中中中中中中alex中中中中中中中中

5. count

# 去字符串中寻找，寻找子序列的出现次数
test = "aLexalexr"
v = test.count('ex')
print(v)   #

test = "aLexalexr"
v = test.count('ex',5,7)
print(v)   #
v = test.count('ex',5,8)
print(v)   #

6. endswith(), startswith()

# 以什么什么结尾
# 以什么什么开始
test = "alex"
v1 = test.endswith('ex')
print(v1)    # False
v2 = test.startswith('ex')
print(v2)    # True

7. isalnum(), isalpha()

# 字符串中是否只包含 字母、数字或汉字
test = "123d好"
v1 = test.isalnum()
print(v1)   # True

# 字符串中是否只包含 字母或汉字
v2 = test.isalpha()
print(v2)   # False

8. isdecimal(), isdigit(), isnumeric()

# test = "二" # 1，② ， 是否为数字
test = ''
v1 = test.isdecimal()
v2 = test.isdigit()    #包含②
v3 = test.isnumeric()  #包含“二”
print(v1,v2,v3)    #True True True

9. isprintable()

# 是否存在不可显示的字符
# \t   制表符
# \n   换行
test = "oiuas\tdfkj"
v = test.isprintable()
print(v)      # False

10. isspace()

# 15 判断是否全部是空格
test = "    "
v = test.isspace()
print(v)     # True

11. istitle(), title()

# 16 判断是否是标题
test = "Return True if all cased characters in S"
v1 = test.istitle()
print(v1)     # False
v2 = test.title()
print(v2)     # Return True If All Cased Characters In S
v3 = v2.istitle()
print(v3)     # True

12. join()

# 17 ***** 将字符串中的每一个元素按照指定分隔符进行拼接
test = "你是风儿我是沙"
print(test)
t = ' '
v = t.join(test)
print(v)     # 你 是 风 儿 我 是 沙

13. islower(), isupper()

# 18 判断是否全部是大小写 和 转换为大小写
test = "Alex"
v1 = test.islower()
v2 = test.lower()
print(v1, v2)     # False alex

v1 = test.isupper()
v2 = test.upper()
print(v1,v2)      # False ALEX

14. lstrip(), rstrip(), strip()

# 移除指定字符串
test = "wxadx"
v1 = test.lstrip('x')
v2 = test.rstrip('x')
v3 = test.strip('x')
print(v1,v2,v3)    # wxadx wxad wxad

# 去除左右空白
v = '  df  '
print(v)     # '  df  '
v1 = v.lstrip()
v2 = v.rstrip()
v3 = v.strip()
print(v1)    # 'df  '
print(v2)    # '  df'
print(v3)    # 'df'

15. maketrans(), translate()

# 对应关系替换
test =  "aeiou"
test1 = ""

v = "asidufkasd;fiuadkf;adfkjalsdjf"
m = str.maketrans("aeiou", "")
new_v = v.translate(m)
print(new_v)     # 1s3d5fk1sd;f351dkf;1dfkj1lsdjf

16. partition(), rpartition()

# 21 分割为三部分
test = "testasdsddfg"
v = test.partition('s')
print(v)     # ('te', 's', 'tasdsddfg')
v = test.rpartition('s')
print(v)     # ('testasd', 's', 'ddfg')

17. split(), rsplit()

# 分割为指定个数
test = "testasdsddfg"
v1 = test.split('s',2)
print(v1)     # ['te', 'ta', 'dsddfg']
v2 = test.rsplit('s',2)
print(v2)     # ['testa', 'd', 'ddfg']

18. splitlines()

# 分割，只能根据，true，false：是否保留换行
test = "asdfadfasdf\nasdfasdf\nadfasdf"
v1 = test.splitlines(True)
print(v1)     # ['asdfadfasdf\n', 'asdfasdf\n', 'adfasdf']
v2 = test.splitlines(False)
print(v2)     # ['asdfadfasdf', 'asdfasdf', 'adfasdf']

19. swapcase()

# 大小写转换
test = "aLex"
v = test.swapcase()
print(v)     # AlEX

20. replace()

# 将指定字符串替换为指定字符串
test = "alexalexalex"
v = test.replace("ex",'bbb')
print(v)     #全部替换
v = test.replace("ex",'bbb',2)
print(v)     #替换前两个

三、4个灰魔法：所有地方都能用

1. for循环

test = "郑建文妹子有种冲我来"
for item in test:
    print(item)     

郑
建
文
妹
子
有
种
冲
我
来

2、索引

# 二、索引，下标，获取字符串中的某一个字符
test = '123dg'
v = test[3]
print(v)     # d

3、切片

# 三、切片
test = '12df56'
v = test[0:2]
print(v)     # 12d

4 、获取长度

# 四、获取长度
# Python3： len获取当前字符串中由几个字符组成
test = 'asdfg'
v = len(test)
print(v)     #

四、一个深灰魔法

###################### 1个深灰魔法 ######################
# 字符串一旦创建，不可修改
# 一旦修改或者拼接，都会造成重新生成字符串

# name = "zhengjianwen"
# age = "18"
#
# info = name + age
# print(info)