This article introduces how to use regular expressions to match characters in PHP. If you need help, please refer to it.
1. Characters For a single character, it is usually expressed literally. The character indicates that the following character is a special character, so it is not interpreted literally, but is interpreted as a special character. For example, /b/ is equivalent to the character b. By adding a backslash in front of b, which is / /, the character becomes a special character, indicating the dividing line of matching a word. For several characters, it is usually stated that they are special, and the symbol indicates that the characters that follow are not special and should be interpreted literally 2.Character* Indicates that the matching character must be at the front. For example, the /^A/ character does not match the A in an A, but matches the first a in an A. 3. Character $ Similar to the ^ character, but matches the last character. For example, /t$/ does not match the t in the eater character, but matches the t in the eat character. 4.Character* Matches the character preceding the * character 0 or n times. For example, /bo*/ matches the boooo in A ghost booooed or the b in A bird warbled, but does not match any of the characters in A goat grunted. 5, character + Matches the character preceding the + character 1 or n times, equivalent to {1,}. For example, /a+/ matches a in the candy character and all a in the caaaaaaaaaaaady character. 6. Characters? Match? 0 or 1 times of the character preceding the character. For example, /e?le?/ matches el in the angel character and le in the angle character. 7. Character . (pay attention, it’s a dot) The . character matches any single character except newlines. For example, /.n/ matches nay, an apple is on the tree characters an and on, but does not match nay. 8, character (x) Match x characters and log the matching value. 9. Character x|y Match x or y. 10, characters {n} Here n is a positive integer, which means matching the previous n characters. For example, /a{2}/ does not match the a in "candy", but matches all a's in "caandy" and the first two a's in "caaaandy". 11. Character {n,} Here n is a positive integer, which means matching at least n previous characters. For example, /a{2}/ does not match the a in "candy", but matches all a's in "caandy" and all a's in "caaaandy". 12. Character {n,m} Here n and m are both positive integers, which means matching at least n and at most m previous characters. 13. Character [xyz] A list of characters that matches any character in the list. Character ranges can be indicated by hyphens -. For example, [abcd] and [a-d] are the same, they match b in brisket and c in echo. 14, character [^xyz] One-character complement, which matches everything except the listed characters. A range of characters can be indicated by a hyphen -. For example, [^abcd] and [^a-d] are equivalent. They match the r in brisket and the h in echo. 15, characters (space) Match a space 16, characters Matches a word boundary, such as a space. For example, /nw/ matches no in noonday, and /wy/ matches ly in "possible yesterday". Note: Specifies that the matching pattern must appear at one of the 2 boundaries at the beginning or end of the target character. 1 2 Next Page Last Page |