PHP RegEx Basics
| Regular Expression | Will match... |
| foo | The string "foo" |
| ^foo | "foo" at the start of a string |
| foo$ | "foo" at the end of a string |
| ^foo$ | "foo" when it is alone on a string |
| [abc] | a, b, or c |
| [a-z] | Any lowercase letter |
| [^A-Z] | Any character that is not a uppercase letter |
| (gif|jpg) | Matches either "gif" or "jpeg" |
| [a-z]+ | One or more lowercase letters |
| [0-9.-] | Аny number, dot, or minus sign |
| ^[a-zA-Z0-9_]{1,}$ | Any word of at least one letter, number or _ |
| ([wx])([yz]) | wy, wz, xy, or xz |
| [^A-Za-z0-9] | Any symbol (not a number or a letter) |
| ([A-Z]{3}|[0-9]{4}) | Matches three letters or four numbers |
| Operator Type | Examples | Description |
|---|---|---|
| Literal Characters Match a character exactly | a A y 6 % @ | Letters, digits and many special characters match exactly |
| $ ^ + \ ? | Precede other special characters with a to cancel their regex special meaning | |
| Literal new line, tab, return | ||
| cJ cG | Control codes | |
| xa3 | Hex codes for any character | |
| Anchors and assertions | ^ | Field starts with |
| $ | Field ends with | |
| [[:<:]] | Word starts with | |
| [[:>:]] | Word ends with | |
| Character groups any 1 character from the group | [aAeEiou] | any character listed from [ to ] |
| [^aAeEiou] | any character except aAeEio or u | |
| [a-fA-F0-9] | any hex character (0 to 9 or a to f) | |
| . | any character at all | |
| [[:space:]] | any space character (space or ) | |
| [[:alnum:]] | any alphanumeric character (letter or digit) | |
| Counts apply to previous element | + | 1 or more ("some") |
| * | 0 or more ("perhaps some") | |
| ? | 0 or 1 ("perhaps a") | |
| {4} | exactly 4 | |
| {4,} | 4 or more | |
| {4,8} | between 4 and 8 | |
| Add a ? after any count to turn it sparse (match as few as possible) rather than have it default to greedy | ||
| Alternation | | | either, or |
| Grouping | ( ) | group for count and save to variable |
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