Register

#TOC DOUBT

1,067 views
0 votes
0 votes

Let L be the set of letters {_,A,B,...Z,a,b,…z} and D be the set of digits {0,1…9}. Then which of the following regular expression represents the set of valid C identifiers. Assume that any C keyword is also allowed as variable name.

  1.  L*(L+D)*
  2.  LL*D*
  3.  L(L+D)*
  4.   None of the above

Please explain with valid reason..?

Thanks,

User Avatar

1 Answer

2 votes
2 votes

In this question the premise assumes that we are only talking about identifier construction with digits and letter as given in form of two sets , D and L.

The regular expression is:= L(L+D)* because the first character in naming an identifier should be a letter then it can be followed by any digit or letter.

Hence the answer is C.

I am providing a snapshot which gives a similar regular expression for C identifier construction:

User Avatar
Voting & Accepting an answer helps improve the community
← PreviousNext →
← Previous in categoryNext in category →

Related questions

3 votes
3 votes
1 answer
1
ashishgateashish asked Mar 13, 2018
1,156 views
#TOC Doubt - Regular expressions
Part A: Given : (b|ab*ab*)* How can it be interpreted as: 1.((b+ab*)ab*)* 2.(b+(ab*ab*))* 3.((b+a)b*ab*)* Part B: 1.What will be its NFA ? 2.Can we draw a direct MINIMAL DFA for such questions?
Part A:Given : (b|ab*ab*)* How can it be interpreted as:1.((b+ab*)ab*)* 2.(b+(ab*ab*))*3.((b+a)b*ab*)*Part B:1.What will be its NFA ? 2.Can we draw a direct MINIMAL DFA f...
User Avatar
0 votes
0 votes
0 answers
2
iarnav asked Jan 30, 2018
202 views
#TOC Doubt
L = anbm / n,m>=1 What type pf Language is this? Also, please tell are n,m are independent or dependent i.e can we have like n=2 and m=3 or both n,m have to have same values!?
L = anbm / n,m>=1What type pf Language is this? Also, please tell are n,m are independent or dependent i.e can we have like n=2 and m=3 or both n,m have to have same valu...
User Avatar
0 votes
0 votes
0 answers
3
prabhath challa asked 1 day ago
18 views
#TOC regular expression
what will be the regular expression of this DFA using Arden's theorem
what will be the regular expression of this DFA using Arden's theorem
User Avatar
Link Copied!