what uppercase alpha character

If "^" is displayed in "[]", this expression does not match the characters in, for example, "/[^ a-z]/" does not match any lower-case letters! The regular expression provides the following default values:'[: Alnum:]' matches any letterAlphanumeric

If "^" appears in "[]", this expression does not match the characters appearing in "[]", such as "/[^a-z]/" does not match any lowercase letters! And the regular expression gives several default values for "[]", as follows: ' [: alnum:] ' matches

Use of Cctype header files in C + +The header file Cctype (character processing library) defines the library function for character judgment and processing, including the header file before use:#include using namespace Std;The list of commonly used

PHP extension text processing -- PCRE regular expression syntax 6 -- Character class (square brackets) and optional path (|) Character class (square brackets) The left square brackets start the description of a character class and end with square

C Language: Wide character set operation function (Unicode encoding) character classification: wide character function general C function Description Iswalnum () isalnum () test character is a number or letter Iswalpha () is Alpha () test

Linux under wildcard characters commonly used to search for files Ls,findSymbolic meaning* represents any character of any length? Represents any single character[] represents any single character within the specified range[-] such as [A-z]

[: Alnum:]: character [: alpha:]: character [: digit:]: digit character [: graph:]: non-empty characters (non-space, control characters) [: lower:]: lowercase character [: cntrl:]: Control Character [: print:]: non-empty characters (including spaces)

The bracket character set in Linux:[:d Igit:] numeric characters, 0-9;[: Lower:] Lowercase alphabetic characters, A-Z;[: Upper:] Uppercase characters, A-Z;[: Alpha:] Uppercase and lowercase alphabetic characters, a-za-z;[: Alnum:] numbers,

A. Regular Expressions:Metacharacters is a character used to illustrate the meaning of a character expression, in short, a character used to describe a character.The regular expression re (Regular expression) is a string of characters consisting of

Basic Regular ExpressionsMatch characters:. : matches any single character. []: matches characters within a specified range[::] : Character Set[: space:] Space character[: Lower:] Lowercase Letters[: Upper:] Uppercase Letters[: Alpha:] uppercase