Representing identifiers using Regular Expression

Question

The regular definition for recognizing identifiers in C programming language is given by

letter -> a|b|...z|A|B|...|Z|_
digit -> 0|1|...|9
identifier -&g         


        

Answer 1

The regular expression you are looking for is:

[_a-zA-Z][_a-zA-Z0-9]{0,30}

It will match an underscore or letter following by X underscores, letters or numbers, where 0 <= X <= 30