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python判斷字符串,str函數isdigit、isdecimal、isnumeric的區別

字符串 4.0 eric 8.0 ssp err must isa isn

s為字符串
s.isalnum() 所有字符都是數字或者字母
s.isalpha() 所有字符都是字母
s.isdigit() 所有字符都是數字
s.islower() 所有字符都是小寫
s.isupper() 所有字符都是大寫
s.istitle() 所有單詞都是首字母大寫,像標題
s.isspace() 所有字符都是空白字符、\t、\n、\r

判斷是整數還是浮點數
a=123
b=123.123

>>>isinstance(a,int)
True
>>>isinstance(b,float)
True
>>>isinstance(b,int)
False

python中str函數isdigit、isdecimal、isnumeric的區別

num = "1" #unicode
num.isdigit() # True
num.isdecimal() # True
num.isnumeric() # True

num = "1" # 全角
num.isdigit() # True
num.isdecimal() # True
num.isnumeric() # True

num = b"1" # byte
num.isdigit() # True
num.isdecimal() # AttributeError ‘bytes‘ object has no attribute ‘isdecimal‘
num.isnumeric() # AttributeError ‘bytes‘ object has no attribute ‘isnumeric‘

num = "IV" # 羅馬數字
num.isdigit() # True
num.isdecimal() # False
num.isnumeric() # True

num = "四" # 漢字
num.isdigit() # False
num.isdecimal() # False
num.isnumeric() # True

===================
isdigit()

True: Unicode數字,byte數字(單字節),全角數字(雙字節),羅馬數字
False: 漢字數字
Error: 無

isdecimal()
True: Unicode數字,,全角數字(雙字節)
False: 羅馬數字,漢字數字
Error: byte數字(單字節)

isnumeric()
True: Unicode數字,全角數字(雙字節),羅馬數字,漢字數字
False: 無
Error: byte數字(單字節)

================
import unicodedata

unicodedata.digit("2") # 2
unicodedata.decimal("2") # 2
unicodedata.numeric("2") # 2.0

unicodedata.digit("2") # 2
unicodedata.decimal("2") # 2
unicodedata.numeric("2") # 2.0

unicodedata.digit(b"3") # TypeError: must be str, not bytes
unicodedata.decimal(b"3") # TypeError: must be str, not bytes
unicodedata.numeric(b"3") # TypeError: must be str, not bytes

unicodedata.digit("Ⅷ") # ValueError: not a digit
unicodedata.decimal("Ⅷ") # ValueError: not a decimal
unicodedata.numeric("Ⅷ") # 8.0

unicodedata.digit("四") # ValueError: not a digit
unicodedata.decimal("四") # ValueError: not a decimal
unicodedata.numeric("四") # 4.0

#"〇","零","一","壱","二","弐","三","參","四","五","六","七","八","九","十","廿","卅","卌","百","千","萬","萬","億"

python判斷字符串,str函數isdigit、isdecimal、isnumeric的區別