\\.<\/code><\/li><\/ul>\n\n\n\nV\u00ed d\u1ee5 \u0111\u1ec3 kh\u1edbp ng\u00e0y th\u00e1ng c\u00f3 c\u1ea5u tr\u00fac ki\u1ec3u nh\u01b0 2.3 (ng\u00e0y m\u00f9ng 2 th\u00e1ng 3) b\u1ea1n s\u1ebd ph\u1ea3i vi\u1ebft th\u1ebf n\u00e0y \\d\\.\\d<\/code> (tr\u00f4ng v\u1eabn qu\u00e1i d\u1ecb nh\u01b0ng gi\u1edd d\u1ec5 hi\u1ec3u h\u01a1n r\u1ed3i! N\u00f3 c\u00f3 ngh\u0129a l\u00e0 s\u1ed1 r\u1ed3i ti\u1ebfp \u0111\u1ebfn l\u00e0 . r\u1ed3i l\u1ea1i l\u00e0 s\u1ed1)<\/p>\n\n\n\n- V\u00ed d\u1ee5 tr\u00ean \u0111\u00e3 \u00e2m th\u1ea7m n\u00f3 \u0111\u1ebfn m\u1ed9t th\u1ee9 ph\u1ee9c t\u1ea1p h\u01a1n \u0111\u00f3 l\u00e0 th\u1ee9 t\u1ef1 trong RegEx. \\d ch\u1ec9 \u0111\u1ea1i di\u1ec7n cho m\u1ed9t s\u1ed1, c\u0169ng v\u1eady [0-9] c\u0169ng ch\u1ec9 \u0111\u1ea1i di\u1ec7n cho m\u1ed9t s\u1ed1 khi m\u00e0 c\u00f3 s\u1ef1 k\u1ebft h\u1ee3p;<\/li>
- N\u1ebfu ch\u1ec9 c\u00f3
\\d<\/code> n\u00f3 s\u1ebd kh\u1edbp v\u1edbi c\u1ea3 67 l\u1eabn 6, nh\u01b0ng n\u1ebfu l\u00e0 \\d\\d<\/code> th\u00ec ch\u1ec9 67 l\u00e0 kh\u1edbp, 6 l\u00fac n\u00e0y kh\u00f4ng li\u00ean quan n\u1eefa. V\u00ec \\d\\d<\/code> n\u00f3i r\u1eb1ng chu\u1ed7i c\u1ea7n t\u00ecm ph\u1ea3i c\u00f3 2 s\u1ed1 c\u01a1.<\/li>- C\u0169ng v\u1eady \\d\\.\\d c\u0169ng ch\u1ec9 kh\u1edbp v\u1edbi 6.7 ho\u1eb7c 5.3 ch\u1ee9 23, 45 l\u00fac n\u00e0y kh\u00f4ng li\u00ean quan n\u1eefa v\u00ec 23 v\u00e0 45 l\u00e0m g\u00ec c\u00f3 d\u1ea5u .<\/li>
- T\u01b0\u01a1ng t\u1ef1 [a-z][a-z] th\u00ec n\u00f3 s\u1ebd ch\u1ec9 kh\u1edbp v\u1edbi chu\u1ed7i n\u00e0o c\u00f3 2 k\u00fd t\u1ef1 \u0111\u1ee9ng c\u1ea1nh nhau ch\u1ee9 c\u00f3 1 k\u00fd t\u1ef1 l\u00e0 kh\u00f4ng kh\u1edbp n\u1eefa, ho\u1eb7c k\u1ec3 c\u1ea3 c\u00f3 2 k\u00fd t\u1ef1 nh\u01b0ng ng\u0103n nhau b\u1eb1ng d\u1ea5u c\u00e1ch nh\u01b0 n\u00e0y
a b<\/code> c\u0169ng kh\u00f4ng kh\u1edbp. Mu\u1ed1n kh\u1edbp v\u1edbi chu\u1ed7i a b<\/code> th\u00ec RegEx s\u1ebd ph\u1ea3i l\u00e0 [a-z]\\s[a-z]<\/code><\/li><\/ul>\n\n\n\nGi\u1edd ch\u00fang ta s\u1ebd \u0111i gi\u1ea3i th\u00edch v\u1ea5n \u0111\u1ec1 l\u00e0 t\u1ea1i sao \\d th\u00ec kh\u1edbp v\u1edbi c\u1ea3 67 v\u00e0 6, m\u00e0 \\d\\d th\u00ec l\u1ea1i ch\u1ec9 kh\u1edbp v\u1edbi 67 th\u00f4i ch\u1ee9 kh\u00f4ng c\u00f2n kh\u1edbp v\u1edbi 6 n\u1eefa. C\u00e1i n\u00e0y r\u1ea5t quan tr\u1ecdng \u0111\u1ea5y \u1ea1, t\u00f4i c\u0169ng ch\u1ec9 v\u1eeba m\u1edbi nh\u1eadn ra, v\u00ec \\d c\u0169ng ch\u1ec9 c\u00f3 m\u1ed9t s\u1ed1 th\u00f4i sao n\u00f3 l\u1ea1i kh\u1edbp \u0111\u01b0\u1ee3c v\u1edbi s\u1ed1 c\u00f3 2 s\u1ed1 l\u00e0 67 kia?<\/p>\n\n\n\n
\u0110i\u1ec1u \u0111\u1ea7u ti\u00ean b\u1ea1n c\u1ea7n l\u00e0m l\u00e0 ph\u00f3ng to m\u00e0n h\u00ecnh c\u1ee7a regex101 \u0111\u1ec3 d\u1ec5 quan s\u00e1t.<\/p>\n\n\n\n
V\u1edbi l\u1ec7nh \/d b\u1ea1n s\u1ebd th\u1ea5y n\u00f3 kh\u1edbp v\u1edbi 2 match c\u1ee7a chu\u1ed7i 67 (hai m\u1ea7u xanh nh\u1ea1t v\u00e0 \u0111\u1eadm, b\u1ea1n di con tr\u1ecf chu\u1ed9t v\u00e0o s\u1ebd th\u1ea5y hi\u1ec7n l\u00ean ch\u1eef match 1, match 2). Chu\u1ed7i 6 b\u00ean d\u01b0\u1edbi chi kh\u1edbp 1 l\u1ea7n.<\/p>\n\n\n\n
![\"c\u00e1ch](\"https:\/\/kiencang.net\/wp-content\/uploads\/2021\/08\/reg2.png\")
<\/figure><\/div>\n\n\n\nNh\u01b0 v\u1eady \u1edf \u0111\u00e2y c\u00f3 ngh\u0129a l\u00e0 chu\u1ed7i trong RegEx s\u1ebd \u0111\u01b0\u1ee3c kh\u1edbp t\u1eeb tr\u00e1i qua ph\u1ea3i v\u1edbi chu\u1ed7i c\u1ea7n t\u00ecm (trong v\u00ed d\u1ee5 tr\u00ean l\u00e0 67 v\u00e0 6), n\u1ebfu kh\u1edbp ch\u00ednh x\u00e1c n\u00f3 s\u1ebd \u0111i ti\u1ebfp \u0111\u1ec3 t\u00ecm trong chu\u1ed7i c\u00f2n ph\u1ea7n n\u00e0o kh\u1edbp n\u1eefa kh\u00f4ng.<\/p>\n\n\n\n
Gi\u1edd n\u1ebfu b\u1ea1n \u0111\u00e1nh l\u1ec7nh Rx l\u00e0 \\d\\d<\/code> th\u00ec s\u1ebd ch\u1ec9 c\u00f3 m\u1ed9t kh\u1edbp trong 67, v\u00e0 kh\u00f4ng c\u00f3 kh\u1edbp (match) n\u00e0o trong chu\u1ed7i b\u00ean d\u01b0\u1edbi c\u1ea3 (kh\u00f4ng c\u00f3 m\u00e0u).<\/p>\n\n\n\n![\"c\u00e1ch](\"https:\/\/kiencang.net\/wp-content\/uploads\/2021\/08\/reg3.png\")
<\/figure><\/div>\n\n\n\nM\u1ed9t v\u00ed d\u1ee5 kh\u00e1c cho r\u00f5 r\u00e0ng h\u01a1n. C\u0169ng v\u1eabn l\u00e0 l\u1ec7nh \\d\\d nh\u01b0ng v\u1edbi c\u00e1c chu\u1ed7i nh\u01b0 h\u00ecnh b\u00ean d\u01b0\u1edbi:<\/p>\n\n\n\n
![\"v\u00ed](\"https:\/\/kiencang.net\/wp-content\/uploads\/2021\/08\/reg4.png\")
<\/figure><\/div>\n\n\n\n\u1ede \u0111\u00e2y chu\u1ed7i 111af23<\/code> s\u1ebd t\u00ecm th\u1ea5y 2 v\u1ecb tr\u00ed kh\u1edbp v\u1edbi l\u1ec7nh \\d\\d<\/code> l\u00e0 11 v\u00e0 23<\/p>\n\n\n\nC\u00f2n chu\u1ed7i b\u00ean d\u01b0\u1edbi l\u00e0 12, 34 v\u00e0 24. S\u1ed1 4 \u0111\u00e3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong chu\u1ed7i 24 r\u1ed3i n\u00ean kh\u00f4ng \u0111\u01b0\u1ee3c d\u00f9ng n\u1eefa, v\u00ec v\u1eady kh\u00f4ng c\u00f3 kh\u1edbp 42. V\u00e0 chu\u1ed7i n\u00e0y c\u00f3 3 kh\u1edbp v\u1edbi l\u1ec7nh \\d\\d<\/code><\/p>\n\n\n\nB\u00e2y gi\u1edd b\u1ea1n chuy\u1ec3n m\u00e0n h\u00ecnh v\u1ec1 k\u00edch c\u1ee1 b\u00ecnh th\u01b0\u1eddng \u0111\u01b0\u1ee3c r\u1ed3i. Gi\u1edd ch\u00fang ta s\u1ebd \u0111i v\u00e0o c\u00e1c v\u00ed d\u1ee5 kh\u00e1c c\u1ee7a RegEx.<\/p>\n\n\n\n
- C\u00f3 m\u1ed9t \u0111i\u1ec1u ch\u00fang ta c\u1ea7n \u0111\u1ec3 \u00fd v\u1ec1 RegEx l\u00e0 m\u1ed7i l\u1ec7nh c\u1ee7a n\u00f3 nh\u01b0 l\u00e0 m\u1ed9t \u0111o\u1ea1n v\u0103n \u0111\u1ed9c l\u1eadp. B\u1ea1n c\u00f3 nh\u1edb l\u1ec7nh
[^abc]<\/code> \u0111\u1ec3 kh\u1edbp v\u1edbi c\u00e1c k\u00fd t\u1ef1 \u0111\u01a1n kh\u00f4ng ph\u1ea3i a, b, c? Gi\u1edd b\u1ea1n \u0111o\u00e1n l\u1ec7nh b\u00ean d\u01b0\u1edbi c\u00f3 \u00fd g\u00ec?<\/li><\/ul>\n\n\n\n^abc<\/code><\/pre>\n\n\n\nC\u1ea3 hai tr\u00f4ng c\u00f3 v\u1ebb r\u1ea5t gi\u1ed1ng nhau, v\u00ec \u0111\u1ec1u c\u00f3 ^, c\u1ee9 ki\u1ec3u nh\u01b0 2 t\u1eeb c\u00f3 c\u00f9ng ch\u1eef c\u00e1i v\u1eady, ch\u1eafc l\u00e0 c\u00f3 li\u00ean quan r\u1ed3i?<\/p>\n\n\n\n
Nh\u01b0ng l\u1ea1i kh\u00f4ng li\u00ean quan g\u00ec!<\/p>\n\n\n\n
C\u00e2u l\u1ec7nh tr\u00ean y\u00eau c\u1ea7u chu\u1ed7i c\u1ea7n t\u00ecm ph\u1ea3i b\u1eaft \u0111\u1ea7u b\u1eb1ng chu\u1ed7i abc. T\u1ee9c l\u00e0 n\u00f3 s\u1ebd ch\u1ec9 kh\u1edbp v\u1edbi chu\u1ed7i abc<\/code>, abcde<\/code>, ch\u1ee9 kh\u00f4ng ph\u1ea3i chu\u1ed7i dabc<\/code>, v\u00ec chu\u1ed7i n\u00e0y c\u00f3 d \u0111\u1ee9ng tr\u01b0\u1edbc abc<\/code> r\u1ed3i. N\u1ebfu b\u1ecf d\u1ea5u ^ \u0111i trong RegEx th\u00ec dabc<\/code> c\u0169ng kh\u1edbp.<\/p>\n\n\n\n- Ng\u01b0\u1ee3c l\u1ea1i y\u00eau c\u1ea7u kh\u1edbp \u0111\u1ea7u chu\u1ed7i ^ l\u00e0 kh\u1edbp cu\u1ed1i chu\u1ed7i $, v\u00ed d\u1ee5 abc$ s\u1ebd kh\u1edbp v\u1edbi c\u00e1c chu\u1ed7i nh\u01b0
dabc<\/code>, fffffabc<\/code>, nh\u01b0ng kh\u00f4ng kh\u1edbp v\u1edbi chu\u1ed7i abcd<\/code>, ho\u1eb7c mabcd<\/code><\/li>- L\u1ec7nh
^abc<\/code> v\u00e0 abc$<\/code> s\u1ebd \u0111\u1ec1u kh\u1edbp v\u1edbi chu\u1ed7i abc<\/code> v\u00ec chu\u1ed7i n\u00e0y v\u1eeba l\u00e0 \u0111\u1ea7u v\u1eeba l\u00e0 cu\u1ed1i trong ch\u00ednh n\u00f3;<\/li><\/ul>\n\n\n\nGi\u1edd ch\u00fang ta s\u1ebd chuy\u1ec3n sang ph\u1ea7n ki\u1ec3m so\u00e1t s\u1ed1 l\u1ea7n xu\u1ea5t hi\u1ec7n c\u1ee7a m\u1ed9t k\u00fd t\u1ef1 n\u00e0o \u0111\u00f3. \u0110\u1ec3 d\u1ec5 hi\u1ec3u t\u00f4i s\u1ebd \u0111\u01b0a ra v\u00ed d\u1ee5.<\/p>\n\n\n\n
B\u00e2y gi\u1edd ch\u00fang ta ph\u1ea3i x\u1eed l\u00fd d\u1eef li\u1ec7u ng\u00e0y th\u00e1ng n\u0103m theo chu\u1ea9n dd\/mm\/yyyy. Ch\u01b0a n\u00f3i \u0111\u1ebfn ph\u1ea7n th\u00e1ng v\u00e0 n\u0103m, trong v\u00ed d\u1ee5 n\u00e0y ch\u00fang ta ch\u1ec9 c\u1ea7n quan t\u00e2m \u0111\u1ebfn ng\u00e0y.<\/p>\n\n\n\n
dd kh\u00f4ng ph\u1ea3i l\u00fac n\u00e0o c\u0169ng \u0111\u01b0\u1ee3c vi\u1ebft theo chu\u1ea9n \u0111\u00f3 t\u1ee9c l\u00e0 d\u01b0\u1edbi 10 th\u00ec c\u00f3 s\u1ed1 0 \u0111\u1eb1ng tr\u01b0\u1edbc, v\u00ed d\u1ee5 05\/07\/2015. R\u1ea5t th\u01b0\u1eddng xuy\u00ean \u0111\u1ecbnh d\u1ea1ng n\u00e0y c\u00f3 d\u1ea1ng 5\/7\/2015.<\/p>\n\n\n\n
T\u1ee9c l\u00e0 ng\u00e0y c\u00f3 th\u1ec3 c\u00f3 1 s\u1ed1 ho\u1eb7c 2 s\u1ed1, v\u00e0 quan tr\u1ecdng h\u01a1n, khi n\u00f3 \u1edf d\u1ea1ng 2 s\u1ed1, c\u00f3 th\u1ec3 c\u00f3 s\u1ed1 0 \u0111\u1eb1ng tr\u01b0\u1edbc m\u00e0 v\u1eabn h\u1ee3p l\u1ec7.<\/p>\n\n\n\n
C\u00e2u l\u1ec7nh RegEx \u0111\u1ec3 gi\u1ea3i quy\u1ebft c\u00e1i n\u00e0y l\u00e0:<\/p>\n\n\n\n
0?\\d<\/code><\/pre>\n\n\n\n\u0110i\u1ec3m nh\u1ea5n \u1edf \u0111\u00e2y l\u00e0 d\u1ea5u ?<\/p>\n\n\n\n
Khi d\u1ea5u h\u1ecfi xu\u1ea5t hi\u1ec7n sau m\u1ed9t k\u00fd t\u1ef1 th\u00ec c\u00f3 ngh\u0129a l\u00e0 k\u00fd t\u1ef1 \u0111\u00f3 kh\u00f4ng t\u1ed3n t\u1ea1i ho\u1eb7c ch\u1ec9 xu\u1ea5t hi\u1ec7n m\u1ed9t l\u1ea7n.<\/p>\n\n\n\n
N\u00f3i c\u00e1ch kh\u00e1c, khi t\u00ecm chu\u1ed7i, Regex th\u1ef1c t\u1ebf s\u1ebd ch\u1ea1y 2 chu\u1ed7i ki\u1ec3m tra. M\u1ed9t chu\u1ed7i ch\u1ec9 l\u00e0 \\d<\/code> v\u00e0 m\u1ed9t chu\u1ed7i l\u00e0 0\\d<\/code><\/p>\n\n\n\n- Ti\u1ebfp theo l\u00e0 d\u1ea5u + sau m\u1ed9t k\u00fd t\u1ef1 c\u00f3 ngh\u0129a l\u00e0 k\u00fd t\u1ef1 c\u00f3 th\u1ec3 xu\u1ea5t hi\u1ec7n m\u1ed9t ho\u1eb7c nhi\u1ec1u l\u1ea7n. V\u00ed d\u1ee5 l\u1ec7nh
\\s+<\/code> s\u1ebd kh\u1edbp v\u1edbi abc d<\/code> v\u00e0 abc d<\/code> v\u00e0 ab cd<\/code><\/li>- \u00dd c\u1ee7a
\\s+<\/code> l\u00e0 kho\u1ea3ng tr\u1eafng c\u00f3 th\u1ec3 xu\u1ea5t hi\u1ec7n m\u1ed9t l\u1ea7n ho\u1eb7c nhi\u1ec1u l\u1ea7n. Trong khi \\s c\u0169ng s\u1ebd kh\u1edbp v\u1edbi c\u00e1c chu\u1ed7i tr\u00ean nh\u01b0ng l\u00e0 nhi\u1ec1u match, c\u00f2n v\u1edbi \\s<\/code>+ ch\u1ec9 c\u00f3 1 match trong t\u1eebng chu\u1ed7i. Nh\u1edd v\u1eady b\u1ea1n c\u00f3 th\u1ec3 d\u00f9ng \\s+<\/code> \u0111\u1ec3 x\u00f3a c\u00e1c kho\u1ea3ng tr\u1eafng th\u1eeba.<\/li><\/ul>\n\n\n\nNgo\u00e0i d\u1ea5u ? v\u00e0 +, ch\u00fang ta c\u00f2n m\u1ed9t d\u1ea5u n\u1eefa l\u00e0 *, khi d\u00f9ng sau k\u00fd t\u1ef1 n\u00e0o \u0111\u1ea5y n\u00f3 ch\u1ec9 \u0111\u1ebfn vi\u1ec7c k\u00fd t\u1ef1 \u1ea5y c\u00f3 th\u1ec3 kh\u00f4ng t\u1ed3n t\u1ea1i, ho\u1eb7c l\u1eb7p l\u1ea1i nhi\u1ec1u l\u1ea7n.<\/p>\n\n\n\n
- Ph\u1ea7n ti\u1ebfp theo ch\u00fang ta s\u1ebd n\u00f3i v\u1ec1 vi\u1ec7c ch\u1ec9 \u0111\u1ecbnh c\u1ee5 th\u1ec3 m\u1ed9t k\u00fd t\u1ef1 n\u00e0o \u0111\u00f3 \u0111\u01b0\u1ee3c l\u1eb7p l\u1ea1i bao nhi\u00eau l\u1ea7n.<\/li>
- L\u1ea5y l\u1ea1i v\u00ed d\u1ee5 ng\u00e0y th\u00e1ng n\u0103m. N\u1ebfu ch\u00fang ta \u00e1p d\u1ee5ng chu\u1ea9n n\u0103m g\u1ed3m 4 ch\u1eef s\u1ed1 th\u00ec thay v\u00ec ph\u1ea3i ghi
\\d\\d\\d\\d<\/code> ch\u00fang ta c\u00f3 th\u1ec3 ghi ng\u1eafn g\u1ecdn h\u01a1n b\u1eb1ng c\u00e1ch vi\u1ebft \\d{4}<\/code>, t\u1ee9c chu\u1ed7i \u0111\u00f3 ph\u1ea3i c\u00f3 ch\u00ednh x\u00e1c 4 s\u1ed1;<\/li>- Trong m\u1ed9t v\u00ed d\u1ee5 kh\u00e1c kh\u00f4ng li\u00ean quan \u0111\u1ebfn ng\u00e0y n\u1eefa, v\u1edbi l\u1ec7nh
a{4,}<\/code> \u0111i\u1ec1u \u0111\u00f3 \u0111\u1ed3ng ngh\u0129a v\u1edbi vi\u1ec7c k\u00fd t\u1ef1 a \u0111\u01b0\u1ee3c l\u1eb7p l\u1ea1i t\u1eeb 4 l\u1ea7n tr\u1edf l\u00ean;<\/li>- N\u1ebfu ch\u00fang ta mu\u1ed1n m\u1ed9t k\u00fd t\u1ef1 bi\u1ebfn thi\u00ean trong m\u1ed9t kho\u1ea3ng x\u00e1c \u0111\u1ecbnh v\u00ed d\u1ee5 ch\u1ec9 t\u1eeb 4 \u0111\u1ebfn 6, ch\u00fang ta vi\u1ebft nh\u01b0 sau
a{4,6}<\/code> khi \u0111\u00f3 2aaaa<\/code>, 2aaaaa<\/code>, 2aaaaaa<\/code> \u0111\u1ec1u kh\u1edbp, nh\u01b0ng 2aaa<\/code> s\u1ebd kh\u00f4ng kh\u1edbp v\u00ec s\u1ed1 l\u01b0\u1ee3ng k\u00fd t\u1ef1 a c\u1ee7a n\u00f3 l\u00e0 3. \u0110\u1ed1 b\u1ea1n 2aaaaaaa<\/code> (c\u00f3 7 ch\u1eef a, th\u00ec c\u00e2u l\u1ec7nh RegEx a{4,6}<\/code> c\u00f3 kh\u1edbp kh\u00f4ng?)<\/li><\/ul>\n\n\n\nTh\u1eed c\u00e1i bi\u1ebft li\u1ec1n. Kh\u00e1c v\u1edbi tr\u1ef1c quan, ch\u00fang ta ngh\u0129 7 > 6 th\u00ec s\u1ebd kh\u00f4ng match. Nh\u01b0ng n\u00f3 v\u1eabn match, v\u00ec \u1edf \u0111\u00e2y RegEx v\u1eabn kh\u1edbp \u0111\u01b0\u1ee3c 6 k\u00fd t\u1ef1 \u0111\u1ea7u trong 7 k\u00fd t\u1ef1 a trong chu\u1ed7i 2aaaaaaa<\/code><\/p>\n\n\n\nTi\u1ebfp theo l\u00e0 m\u1ed9t d\u1ea5u d\u1ec5 hi\u1ec3u v\u1edbi \u0111a s\u1ed1 c\u00e1c b\u1ea1n \u0111ang \u0111\u1ecdc b\u00e0i n\u00e0y, \u0111\u00f3 l\u00e0 d\u1ea5u |<\/code>\u0111\u1ec3 ch\u1ec9 l\u00e0 ho\u1eb7c gi\u00e1 tr\u1ecb b\u00ean tr\u00e1i d\u1ea5u | ho\u1eb7c gi\u00e1 tr\u1ecb b\u00ean ph\u1ea3i d\u1ea5u |<\/p>\n\n\n\nV\u00ed d\u1ee5 trong l\u1ec7nh 51|71 n\u00f3 s\u1ebd l\u1ea5y chu\u1ed7i 51 \u0111em \u0111i match v\u1edbi chu\u1ed7i c\u1ea7n t\u00ecm, r\u1ed3i ti\u1ebfp t\u1ee5c l\u1ea5y chu\u1ed7i 71 \u0111i so s\u00e1nh. Ch\u1ec9 c\u1ea7n m\u1ed9t trong 2 chu\u1ed7i match l\u00e0 \u0111\u01b0\u1ee3c.<\/p>\n\n\n\n
T\u00f4i s\u1ebd k\u1ebft th\u00fac b\u00e0i n\u00e0y v\u1edbi hai c\u00fa ph\u00e1p m\u00e0 b\u1ea3n th\u00e2n v\u1eabn l\u0103n t\u0103n ch\u01b0a hi\u1ec3u h\u1ebft, nh\u01b0ng v\u1eabn \u0111\u00e1nh li\u1ec1u tr\u00ecnh b\u00e0y. M\u1ecdi ng\u01b0\u1eddi th\u1ea5y sai th\u00ec s\u1eeda nh\u00e9. <\/p>\n\n\n\n
\u0110\u00f3 l\u00e0 l\u1ec7nh \\b<\/code> v\u00e0 ngo\u1eb7c \u0111\u01a1n ()<\/code><\/p>\n\n\n\nT\u00f4i s\u1ebd c\u1ea7n d\u00f9ng v\u00ed d\u1ee5 \u0111\u1ec3 ch\u00fang ta t\u00ecm hi\u1ec3u l\u1ec7nh n\u00e0y.<\/p>\n\n\n\n
H\u00e3y quay l\u1ea1i l\u1ec7nh RegEx chu\u1ea9n ch\u1ec9nh \u0111\u1ec3 ki\u1ec3m tra ch\u00ednh x\u00e1c \u0111\u1ecbnh d\u1ea1ng ng\u00e0y th\u00e1ng n\u0103m.<\/p>\n\n\n\n
\\b(0?[1-9]|[12]\\d|3[01])[\\\/\\-.](0?[1-9]|[12]\\d|3[01])[\\\/\\-.](\\d{2}|\\d{4})\\b<\/code><\/pre>\n\n\n\nGi\u1edd ch\u00fang ta s\u1ebd ph\u00e2n t\u00edch t\u1eebng c\u00e1i m\u1ed9t:<\/p>\n\n\n\n
0?[1-9]<\/code> ngh\u0129a l\u00e0 s\u1ebd c\u1ea7n match \u0111\u1ecbnh ng\u00e0y c\u00f3 s\u1ed1 0 \u0111\u1eb1ng tr\u01b0\u1edbc v\u00ed d\u1ee5 nh\u01b0 05, v\u00e0 k\u1ec3 c\u1ea3 \u0111\u1ecbnh d\u1ea1ng kh\u00f4ng c\u00f3 s\u1ed1 0, v\u00ed d\u1ee5 5. D\u00f9ng 0?[1-9]<\/code> l\u00e0 ch\u00ednh x\u00e1c thay v\u00ec d\u00f9ng 0?\\d<\/code> <\/li>- \u0110\u1ed1 b\u1ea1n bi\u1ebft t\u1ea1i sao? C\u00e2u tr\u1ea3 l\u1eddi l\u00e0 n\u1ebfu \u0111\u1ec3
0?\\d<\/code> th\u00ec \u0111\u1ecbnh d\u1ea1ng sai 00 v\u1eabn \u0111\u01b0\u1ee3c ph\u00e9p (v\u00ec \\d bao g\u1ed3m t\u1eeb 0 \u0111\u1ebfn 9);<\/li>[12]\\d<\/code> c\u00e1i n\u00e0y c\u00f3 ngh\u0129a l\u00e0 n\u00f3 match v\u1edbi kho\u1ea3ng 10 cho \u0111\u1ebfn 29;<\/li>3[01]<\/code> c\u00e1i n\u00e0y c\u00f3 ngh\u0129a l\u00e0 n\u00f3 match v\u1edbi 30 ho\u1eb7c 31<\/li>- Nh\u01b0 v\u1eady b\u1eb1ng c\u1ee5m
0?[1-9]|[12]\\d|3[0\\1]<\/code> n\u00f3 \u0111\u00e3 kh\u1ed1ng ch\u1ebf gi\u00e1 tr\u1ecb ch\u1ec9 g\u1ed3m 2 s\u1ed1 v\u00e0 ch\u1ea1y t\u1eeb kho\u1ea3ng 01 cho \u0111\u1ebfn 31, t\u1ee9c l\u00e0 gi\u00e1 tr\u1ecb h\u1ee3p l\u1ec7 c\u1ee7a m\u1ed9t ng\u00e0y<\/li>- Ti\u1ebfp theo l\u00e0 c\u1ee5m
[\\\/\\-.]<\/code> ch\u00fang ta bi\u1ebft r\u1eb1ng k\u00fd t\u1ef1 \u0111\u1ec3 trong d\u1ea5u ngo\u1eb7c vi\u1ec7c ch\u1ec9 \u0111\u1ec3 ho\u1eb7c, nh\u01b0 tr\u01b0\u1eddng h\u1ee3p [abc] ngh\u0129a l\u00e0 l\u1ea5y m\u1ed9t k\u00fd t\u1ef1 r\u1ed3i l\u1ea7n l\u01b0\u1ee3t \u0111em \u0111i match;<\/li>- C\u00f3 l\u1ebd b\u1ea1n ngh\u0129 ch\u1ec9 c\u1ea7n vi\u1ebft
[\/-.]<\/code> l\u00e0 \u0111\u1ee7, sao l\u1ea1i c\u1ea7n th\u00eam hai d\u1ea5u \\ l\u00e0m g\u00ec. L\u00fd do v\u00ec c\u00e1c k\u00fd t\u1ef1 n\u00e0y tr\u00f9ng v\u1edbi l\u1ec7nh c\u1ee7a RegEx, t\u00f4i c\u00f2n ngh\u0129 \u0111\u00e1ng ra ph\u1ea3i c\u1ea7n 3 d\u1ea5u \\, cho c\u1ea3 d\u1ea5u . n\u1eefa, ngh\u0129a l\u00e0 ph\u1ea3i th\u1ebf n\u00e0y [\\\/\\-\\.]<\/code> m\u1edbi an t\u00e2m. Th\u1ef1c ra 2 \\ l\u1ec7nh v\u1eabn ch\u1ea1y ch\u00ednh x\u00e1c.<\/li>- Ngo\u00e0i c\u00e1ch d\u00f9ng
[\\\/\\-\\.]<\/code> c\u00e1c b\u1ea1n c\u00f3 th\u1ec3 d\u00f9ng (\\\/|\\-|\\.)<\/code> c\u0169ng cho k\u1ebft qu\u1ea3 t\u01b0\u01a1ng t\u1ef1;<\/li>- 2 ph\u1ea7n ti\u1ebfp theo l\u00e0 c\u00e2u l\u1ec7nh t\u01b0\u01a1ng t\u1ef1 2 ph\u1ea7n \u0111\u1ea7u. L\u00fd do kh\u00f4ng ch\u1eafc ch\u1eafn c\u1ee5m s\u1ed1 \u1edf gi\u1eefa \u0111\u00e3 ch\u1ec9 th\u00e1ng n\u00ean ch\u00fang ta v\u1eabn \u0111\u1ec3 kho\u1ea3ng thay \u0111\u1ed5i t\u1eeb 0 t\u1edbi 31;<\/li>
- Ph\u1ea7n cu\u1ed1i l\u00e0 \u0111o\u1ea1n
\\d{2}|\\d{4}<\/code> ch\u00fang ta hi\u1ec3u r\u1eb1ng c\u00e1i n\u00e0y y\u00eau c\u1ea7u kh\u1edbp {2} s\u1ed1\\d ho\u1eb7c| {4} s\u1ed1\\d. T\u01b0\u01a1ng \u1ee9ng v\u1edbi \u0111\u1ecbnh d\u1ea1ng yy ho\u1eb7c yyyy c\u1ee7a n\u0103m;<\/li>- Nh\u01b0 v\u1eady l\u00e0 c\u1ea5u tr\u00fac c\u1ee7a l\u1ec7nh RegEx \u0111\u01b0\u1ee3c hi\u1ec3u t\u01b0\u01a1ng \u0111\u1ed1i r\u00f5 v\u00e0 n\u00f3 ph\u00f9 h\u1ee3p v\u1edbi \u0111\u1ecbnh d\u1ea1ng d\u1eef li\u1ec7u m\u00e0 ch\u00fang ta mu\u1ed1n so kh\u1edbp;<\/li><\/ul>\n\n\n\n
B\u00e2y gi\u1edd l\u00e0 c\u00e2u h\u1ecfi quan tr\u1ecdng, d\u1ea5u ()<\/code> c\u00f3 th\u1ec3 hi\u1ec3u \u0111\u01a1n gi\u1ea3n l\u00e0 nh\u00f3m c\u00e1c chu\u1ed7i c\u1ea7n ki\u1ec3m tra tr\u01b0\u1edbc. V\u1eady \/b<\/code> \u0111\u1ec3 l\u00e0m g\u00ec?<\/p>\n\n\n\nKhi c\u00e2u l\u1ec7nh chu\u1ea9n 4 chu\u1ed7i d\u01b0\u1edbi \u0111\u00e2y kh\u1edbp:<\/p>\n\n\n\n
- 01-15-2017<\/strong><\/li>
- 11\/05\/2017<\/strong><\/li>
- 1\/05\/17<\/strong><\/li>
- 05\/1\/17<\/strong><\/li><\/ul>\n\n\n\n
C\u00f2n 3 chu\u1ed7i d\u01b0\u1edbi \u0111\u00e2y kh\u00f4ng kh\u1edbp b\u1ea5t k\u00fd match n\u00e0o:<\/p>\n\n\n\n
![\"Giao](\"https:\/\/kiencang.net\/wp-content\/uploads\/2021\/08\/regex101-1024x500.png\")
<\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/kiencang.net\/wp-content\/uploads\/2021\/08\/reg1.png\")
<\/figure><\/div>\n\n\n\n