字符串

##字符串

判断回文数 ：
x = "12321"
"是回文数" if x == x[::-1] else "不是回文数"
'是回文数'
x = "12345"
"是回文数" if x == x[::-1] else "不是回文数"
'不是回文数'

大小写字母换来换去的方法：
capitalize() casefold() title() swapcase() upper() lower()

#代码：
x = "I love Filish"
x.capitalize()
'I love filish'
x
'I love Filish'
x.casefold()
'i love filish'
x.title()
'I Love Filish'
x.swapcase()
'i LOVE fILISH'
x.upper()
'I LOVE FILISH'
x.lower()
'i love filish'

左中右对其方法 ：
center(width,fillchar='') ljust(width,fillchar='')
rjust(width,fillchar='') zfill(width)

#代码：
x = "有内鬼,停止交易！"
x.center(5)
'有内鬼,停止交易！'
x.center(15)
' 有内鬼,停止交易！ '
x.ljust(15)
'有内鬼,停止交易！ '
x.rjust(15)
' 有内鬼,停止交易！'
x.zfill(5)
'有内鬼,停止交易！'

查找方法 ：
count(sub[,start[,end]])
find(sub[,start[,end]]) rfind(sub[,start[,end]]) index(sub[,start[,end]]) rundex(sub[,start[,end]])

#代码：
x = "上海自来水来自海上"
x.count("海")
2
x.count("海",0,5)
1
x.find("海")
1
x.rfind("海")
7
x.find("鬼")
-1

替换方法：
expandtabs([tabsize=8]) replace(old,new,count=-1) translate(table)

#代码：
"在吗?我在你家楼下,快点下来!".replace("在吗","想你")
'想你?我在你家楼下,快点下来!'
table = str.maketrans("ABCDEFG","1234567")
"I love Y".translate(table)
'I love Y'
"I love wife".translate(table)
'I love wife'
"I love wife".translate(str.maketrans("ABCDEFG","1234567"))
'I love wife'
"I love wife".translate(str.maketrans("ABCDEFG","1234567","love"))
'I wif'

判断方法：14个
startswith[,start[,end]])

x = "我爱Python"
x.startswith("我")
True
x.startswith("小甲鱼")
False
x.endswith("Python")
True
x.endswith("Py")
False
x.startswith("我",1)
False
x.startswith("爱",1)
True
x.endswith("Py",0,4)
True
x = "他爱Python"
if x.startswith(("你","我","他")):
print("总有人喜欢Python")

总有人喜欢Python
x = "I love Python"
x.istitle ()
False
x.isupper ()
False
x.upper ().isupper()
True
x.isalpha ()
False
"Iloveyou".isalpha ()
True

" \n".isspace()
True
x.isprintable ()
True
"I love you\n".isprintable ()
False
x = "12345"
x.isdecimal ()
True
x.isdigit ()
True
x.isnumeric ()
True
x = "2^2"
x.isdecimal ()
False
x.isdigit ()
False
x.isnumeric ()
False
x = "I II III IV V"
x.isdecimal ()
False
x.isdigit ()
False
x.isnumeric ()
False
"Iam a good boy".isidentifier ()
False
"I_am_a_good_boy".isidentifier ()
True
"flish".isidentifier ()
True
"520fish".isidentifier ()
False
import keyword
keyword.iskeyword("if")
True
keyword.iskeyword("py")
False

截取字符串方法：

代码：
" 左侧不要留白".lstrip ()
'左侧不要留白'
"右侧不要留白 ".rstrip()
'右侧不要留白'
"www.ilovefish.com".lstrip ("wcom")
'.ilovefish.com'
"www.ilovefish.com".rstrip ("wcom")
'www.ilovefish.'
"www.ilovefish.com".removeprefix ("www")
'.ilovefish.com'
"www.ilovefish.com".removesuffix (".com")
'www.ilovefish'

拆分与拼接方法；

#代码：
"苟日新，日日新，又日新".split ()
['苟日新，日日新，又日新']
"苟日新，日日新，又日新".split (',')
['苟日新，日日新，又日新']
"苟日新，日日新，又日新".rsplit (',')
['苟日新，日日新，又日新']
"苟日新，日日新，又日新".split (',',1)
['苟日新，日日新，又日新']
"苟日新，日日新，又日新".rsplit (',',1)
['苟日新，日日新，又日新']
"苟日新\n日日新\n又日新".split ('\n')
['苟日新', '日日新', '又日新']
"苟日新\r日日新\r又日新".split ('\r')
['苟日新', '日日新', '又日新']
"苟日新\n日日新\n又日新".splitlines ()
['苟日新', '日日新', '又日新']
".".join(["www","ilovefish","com"])
'www.ilovefish.com'
"^".join(("F","ish","c"))
'F^ish^c'
s = "fish"
s += s
s
'fishfish'
"".join(("fish","fish"))
'fishfish'

格式化字符串的方法：
#代码：
year = 2020
"兵哥工作室成立于 year 年"
'兵哥工作室成立于 year 年'
"兵哥工作室成立于 {} 年".format (year)
'兵哥工作室成立于 2020 年'
"1+2={},2的平方是{},3的立方是{}".format (1+2,2*2,3*3*3)
'1+2=3,2的平方是4,3的立方是27'
"{}看到{}就很激动！".format ("兵哥","漂亮小姐姐")
'兵哥看到漂亮小姐姐就很激动！'
"{1}看到{0}就很激动！".format ("兵哥","漂亮小姐姐")
'漂亮小姐姐看到兵哥就很激动！'
"{0}{0}{1}{1}".format("是","非")
'是是非非'
"我叫{name},我爱{0}.喜爱{0}的人，运气不会差".format ("python",name="兵哥")
'我叫兵哥,我爱python.喜爱python的人，运气不会差'
"{},{},{}".format(1,"{}",2)
'1,{},2'
"{},{{}},{}".format(1,2)
'1,{},2'

 

"{:^}".format(1,2)
'1'
"{:^}".format(250)
'250'
"{:^10}".format(250)
' 250 '
"{1:>10}{0:<10}".format(520,250)
' 250520 '
"{left:>10}{right:<10}".format(right=520,left=250)
' 250520 '
"{:010}".format(-250)
'-000000250'
"{:010}".format("fish")
'fish000000'
"{1:%>10}{0:%<10}".format(520,250)
'%%%%%%%250520%%%%%%%'
"{:0=10}".format(520)
'0000000520'
"{:0=10}".format(-520)
'-000000520'
"{:010}".format("fish")
'fish000000'
"{1:%>10}{0:%<10}".format(520,250)
'%%%%%%%250520%%%%%%%'
"{:0=10}".format(520)
'0000000520'
"{:0=10}".format(-520)
'-000000520'
"{:+}{:-}".format (520,-250)
'+520-250'
"{:,}".format(1234)
'1,234'
"{:_}".format(1234)
'1_234'
"{:,}".format(123)
'123'
"{:,}".format(123456789)
'123,456,789'
"{:.2f}".format(3.1415)
'3.14'
"{:.2g}".format(3.1415)
'3.1'
"{:.6}".format("i love fish")
'i love'
"{:b}".format(80)
'1010000'
"{:c}".format(80)
'P'
"{:d}".format(80)
'80'
"{:o}".format(80)
'120'
"{:x}".format(80)
'50'
"{:#b}".format(80)
'0b1010000'
"{:#o}".format(80)
'0o120'
"{:#x}".format(80)
'0x50'
"{:e}".format(3.1415)
'3.141500e+00'
"{:E}".format(3.1415)
'3.141500E+00'
"{:f}".format(3.1415)
'3.141500'
"{:g}".format(1223456789)
'1.22346e+09'
"{:g}".format(1223.456789)
'1223.46'
"{:%}".format(1.78)
'178.000000%'
"{:.2%}".format(1.78)
'178.00%'
"{:.{prec}f}".format(3.1415,prec=2)
'3.14'
"{:{fill}{align}{width}.{prec}{ty}}".format(3.1415,fill='+',align='^',width=10,prec=3,ty='g')
'+++3.14+++'

f-字符串（f-string）

#代码：
year = 2025
"兵哥工作室成立于{}年".format(year)
'兵哥工作室成立于2025年'
F"兵哥工作室成立于{year}年"
'兵哥工作室成立于2025年'
"1+2={},2的平方是{},3的立方是{}".format (1+2,2*2,3*3*3)
'1+2=3,2的平方是4,3的立方是27'
f"1+2={1+2},2的平方是{2*2},3的立方是{3*3*3}"
'1+2=3,2的平方是4,3的立方是27'
"{:010}".format(-520)
'-000000520'
"{-510:010}"
'{-510:010}'
f"{-510:010}"
'-000000510'
"{:,}".format(123456789)
'123,456,789'
f"{123456789:,}"
'123,456,789'
"{:.2f}".format(3.1415)
'3.14'
f"{3.1414:.2f}"
'3.14'
"{:{fill}{align}{width}.{prec}{ty}}".format(3.1415,fill='+',align='^',width=10,prec=3,ty='g')
'+++3.14+++'
fill = '+'
align = '^'
width = 10
prec = 3
ty = 'g'
f"3.1415:{fill}{align}{width}.{prec}{ty}"
'3.1415:+^10.3g'
f"{3.1415:{fill}{align}{width}.{prec}{ty}}"
'+++3.14+++'