字符串的操作方法（第二天）

a = "2"
b = "②"
c = "二"
v1 = a.isdecimal()
v2 = a.isdigit()
v3 = a.isnumeric()
v4 = b.isdecimal()
v5 = b.isdigit()
v6 = b.isnumeric()
v7 = c.isdecimal()
v8 = c.isdigit()
v9 = c.isnumeric()
print(a,v1,v2,v3)
print(b,v4,v5,v6)
print(c,v7,v8,v9)

2 True True True
② False True True
二 False False True

a = "WCbLyN"
print(a.casefold())     #字符串转变为对应的小写，不止英文
print(a.swapcase())     #将大小写互换
print(a.upper())        #全部转换为大写
print(a.lower())        #全部转换为小写
print(a.title())        #首字母大写，其他小写
print(a.isupper())      #判断是否为大写
print(a.islower())      #判断是否为小写
print(a.istitle())      #判断是否为首字母大写

结果依次为：
wcblyn
wcBlYn
WCBLYN
wcblyn
Wcblyn
False
False
False

a = "WCbLyNWCbLyNWCbLyN"
v = a.find("C",0,2)
v1 = a.find("c")
v2 = a.find("C",0,1)
print(v,v1,v2)                 #显示字符串中第一次出现此字符的位置，也可限定开始和结束的区间，左闭右开，查找失败返回-1

结果依次为：
1 -1 -1

a = "i am {name},age{b}"
v = a.format(name = "wcb",b = 21 )                    
v1 = a.format_map({"name":"lyn","b":21})
print(v)
print(v1)        #格式化，将一个字符串中的占位符替换为指定的值，按顺序填入 

结果为:
i am wcb,age21
i am lyn,age21

a = "lynwcb"
b = "123456"
v = "456 love 123"
m = str.maketrans(b,a)            #将两个参照的字符串一一对应起来
v1 = v.translate(m)                #转换
print(v1)

结果为：
wcb love lyn        

a = "lynwcb596922596922"
v1 = a.replace("wc","love")
v2 = a.replace("w","love")
v3 = a.replace("wc","o")
v4 = a.replace("2","o")
v5 = a.replace("2","o",2)             #可通过添加参数选择替换前n个
print(v1)
print(v2)
print(v3)
print(v4)
print(v5)

结果依次为：
lynloveb596922596922
lynlovecb596922596922
lynob596922596922
lynwcb5969oo5969oo
lynwcb5969oo596922

p = "lynwcblynwcb"
v = p.strip("wcbly")
print(v)

结果为：
nwcblyn

a = "_"
v = "lynwcb596922"
v1 = a.join(v)
print(v1)

结果为：
l_y_n_w_c_b_5_9_6_9_2_2             #在两个字符之间加入，前后没有

a = "lynwcb596922lynwcb596922"
print(a.partition("wc"))
print(a.rpartition("wc"))         #从右边开始检索第一个关键词

结果为：
('lyn', 'wc', 'b596922lynwcb596922')
('lynwcb596922lyn', 'wc', 'b596922')

a = "lynwcb596922lynwcb596922"
print(a.split("cb"))
print(a.split("cb",1))      #其本身取不到.可定参数，确定分几次
print(a.rsplit("cb",1))

结果为：
['lynw', '596922lynw', '596922']
['lynw', '596922lynwcb596922']
['lynwcb596922lynw', '596922']

value = "5 + 9"
v1,v2 = value.split("+")
print(int(v1)+int(v2))

a = "name\tage\tgender\nwcb\t21\tmale\nlyn\t21\tfemale"
print(a.expandtabs(20))                 #20个为一组，若遇到\t,自动补满20

结果为：
name                age                 gender
wcb                 21                  male
lyn                 21                  female

v = range(0,100,5)        #左闭右开 0<=x<100
for i in v:
    print(i)

a = "LYNWCB"
v = a.center(20,"*")            
print(v)

结果为：
*******LYNWCB*******