regex101: Initializing identifiers

Pro

\s*a Unicode whitespace character, repeated any number of times

1st Alternativeint(?:\s+long|\s+short)?

intthe literal text int (case sensitive)

Non-Capturing Group(?:\s+long|\s+short)?

?repeats the group contents below at most once:

1st Alternative\s+long

\s+a Unicode whitespace character, repeated at least once

longthe literal text long (case sensitive)

2nd Alternative\s+short

\s+a Unicode whitespace character, repeated at least once

shortthe literal text short (case sensitive)

2nd Alternativedouble(?:\s+long)?

doublethe literal text double (case sensitive)

Non-Capturing Group(?:\s+long)?

?repeats the group contents below at most once:

\s+a Unicode whitespace character, repeated at least once

longthe literal text long (case sensitive)

3rd Alternative long(?:\s+int|\s+double)?

longthe literal text long (case sensitive)

Non-Capturing Group(?:\s+int|\s+double)?

?repeats the group contents below at most once:

1st Alternative\s+int

\s+a Unicode whitespace character, repeated at least once

intthe literal text int (case sensitive)

2nd Alternative\s+double

\s+a Unicode whitespace character, repeated at least once

doublethe literal text double (case sensitive)

4th Alternativeshort(?:\s+int)?

shortthe literal text short (case sensitive)

Non-Capturing Group(?:\s+int)?

?repeats the group contents below at most once:

\s+a Unicode whitespace character, repeated at least once

intthe literal text int (case sensitive)

5th Alternativefloat

floatthe literal text float (case sensitive)

6th Alternativechar

charthe literal text char (case sensitive)

2nd Alternative (?<error>\w+|\w+\s*\,)

Group error(?<error>\w+|\w+\s*\,)

1st Alternative\w+

\w+a Unicode word character, repeated at least once

2nd Alternative\w+\s*\,

\w+a Unicode word character, repeated at least once

\s*a Unicode whitespace character, repeated any number of times

\,the literal , (44₁₀ / 54₈ / 2C₁₆)

\s+a Unicode whitespace character, repeated at least once

+repeats the group contents below at least once:

2nd Alternative (?<id>[a-zA-Z_][a-zA-Z_0-9]*)

Non-Capturing Group(?:\s*\[\s*[1-9]\d*\s*\])*

\s*a Unicode whitespace character, repeated any number of times

Non-Capturing Group(?:\,\s*|(?=\;))

\s*a Unicode whitespace character, repeated any number of times

\;the literal ; (59₁₀ / 73₈ / 3B₁₆)

\s*a Unicode whitespace character, repeated any number of times

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

25 tokens

Regular Expression

\s*
  (
    (?<type>int(?:\s+long|\s+short)?|double(?:\s+long)?|
      long(?:\s+int|\s+double)?|short(?:\s+int)?|float|char)
    |
    (?<error>\w+|\w+\s*\,)
  )
  \s+
  (?:
    (?:
      (?:
        (?<error>int|double|float|char|long|short|[^,;a-zA-Z_].+?|[^,;]+?(?:\s+\w+?)+)
        |
        (?<id>[a-zA-Z_][a-zA-Z_0-9]*)
      )
      (?:\s*\[\s*[1-9]\d*\s*\])*
    )
    \s*
    (?:\,\s*|(?=\;))
  )+
\s*\;\s*

int 
    abv, cde, doub1lel,ded, cto, int1;
float ng23423, _ga45, 
astories;     
int af  , f;
int a, b, c;int        short              alt   ;
long double fgd  [ 1 ], [1]       ,     wef ;
char _a[1], fi [
    3 
    ] [ 10] [   4   ]  ,g[1];int qw;