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python中str函數(shù)isdigit、isdecimal、isnumeric的區(qū)別

更新時(shí)間:2018-08-03 來(lái)源:黑馬程序員 瀏覽量:

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(shù)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(shù)字,byte數(shù)字(單字節(jié)),全角數(shù)字(雙字節(jié)),羅馬數(shù)字
False: 漢字?jǐn)?shù)字
Error: 無(wú)

isdecimal()
True: Unicode數(shù)字,,全角數(shù)字(雙字節(jié))
False: 羅馬數(shù)字,漢字?jǐn)?shù)字
Error: byte數(shù)字(單字節(jié))

isnumeric()
True: Unicode數(shù)字,全角數(shù)字(雙字節(jié)),羅馬數(shù)字,漢字?jǐn)?shù)字
False: 無(wú)
Error: byte數(shù)字(單字節(jié))

================
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(wàn)","萬(wàn)","億"



作者:黑馬程序員人工智能+python培訓(xùn)學(xué)院 
首發(fā):http://python.itheima.com/

   

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