正則表達式中的\d 和 [0-9]

最近在調試正則表達式時，發現判斷數字的正則表達式中的\d對全角字符判斷的不許，有的能判斷有時候又判斷不出來。而後通過一番搜索發現\d判斷的不僅是0-9,而是一個 Unicode 字符集，

參考這裏的描述：

\d ✓ ✓ Match any character with the Unicode General Category of Nd (Number, Decimal Digit.)

例以下面的測試：

- (void)testDRegex
{
    NSArray *numbers = @[@"a",@"Ａ",@"1",@"１２３４５６",
                         @"㆒㆓㆔",@"⑴⑵⑶",
                         @"①②③④⑤",@"𝟘𝟙𝟚𝟛",
                         @"᮰᮱᮲᮳᮴᮵᮶᮷᮸᮹",@"ⅠⅡⅢⅣⅤⅥ",
                         @"𐒠𐒡𐒢𐒣𐒤𐒥𐒦𐒧𐒨𐒩",@"ⅰⅱⅲⅳⅴⅵⅶⅷⅸⅹⅺⅻ",@"𝍩𝍪𝍫𝍬𝍭𝍮𝍯𝍰𝍱",
                         @"𝟎𝟏",@"𑶨𑶧𑶧",
                         @"𞥐"];
    for (NSString *string in numbers) {
        BOOL mobile1R = [ValidateUtil validateString:string withRegex:@"^\\d*$"];
        NSLog(@"Test \\d method:, string: %@,result: %@",string,@(mobile1R));
    }
}
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輸出結果爲：

Test \d method:, string: １２３４５６,result: 1
 Test \d method:, string: ㆒㆓㆔,result: 0
 Test \d method:, string: ⑴⑵⑶,result: 0
 Test \d method:, string: ①②③④⑤,result: 0
 Test \d method:, string: 𝟘𝟙𝟚𝟛,result: 1
 Test \d method:, string: ᮰᮱᮲᮳᮴᮵᮶᮷᮸᮹,result: 1
 Test \d method:, string: ⅠⅡⅢⅣⅤⅥ,result: 0
 Test \d method:, string: 𐒠𐒡𐒢𐒣𐒤𐒥𐒦𐒧𐒨𐒩,result: 1
 Test \d method:, string: ⅰⅱⅲⅳⅴⅵⅶⅷⅸⅹⅺⅻ,result: 0
 Test \d method:, string: 𝍩𝍪𝍫𝍬𝍭𝍮𝍯𝍰𝍱,result: 0
 Test \d method:, string: 𝟎𝟏,result: 1
 Test \d method:, string: 𑶨𑶧𑶧,result: 1
 Test \d method:, string: 𞥐,result: 1
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能夠明顯看到\d判斷的不僅是0-9等數字。

點擊查看Unicode Characters in the 'Number, Decimal Digit' Category

最後結論：爲了正確匹配0-9數字，仍是隻寫[0-9]吧，不能再寫\d了

參考：

一、http://userguide.icu-project.org/strings/regexp

二、http://fresky.github.io/2013/06/04/d-0-9-difference-in-regex/

三、https://stackoverflow.com/questions/890686/should-i-use-d-or-0-9-to-match-digits-in-a-perl-regex

四、https://stackoverflow.com/questions/16621738/d-is-less-efficient-than-0-9?newsletter=1&nlcode=55866%7cc739