Question

Part II: Regular Expression 1. Chose match(es) for each given basic/extended regular expression (maybe multiple correct matches) and describe the pattern of matched string for 3), 4), 5),6), 11) e.g. (ab+a, (extended regex ) a) ababa b) aba c)abba d)aabba e)aa Answer: b,c; Pattern : The matched string should begin and end with 'a and ‘b' occurs at least once between leading and ending ‘a') ote: 1) to 5)are basic regexes 1) 'a[ab]*a' (a)ababa (b) aaba (c) aabab (d) aabbaa (e)aa 2) 'a(bc)?' (a) abc (b) a(bc)? (c) a(bc (d) a (e) abcbc 3) ind] (a) wind (b) window (c) end(d) good (e)will (a) a+b+c (b) +b (d) x+1 (e) x+a ote: 5) to 12) are extended regexes (a) a+b+c(b) +b (d) x+1 (e) x+a (a)azbc (b) az(c) azbcbc (d) acc (e)acz 7) a.[0-9]' (a)azz (b) a0z (c) a01 (d) a0a (e)aza (a)good! (b) Book. (c) hard? (d) cool?hot (e)nothing

Answer 1

1. a,b,d,e

• The text that will start with 'a', followed by zero or more occurrences of a or b and then end by 'a'.
• c does not follow the pattern match as it ends with b.

2. a,d

• The text that will start with 'a' followed by zero or 1 occurrence of ab.
• b,c and e are incorrect as they do not follow the pattern.

3. a,d

• The text will have a single character except for the new line and then followed by 0 or more occurrences of I, n, and d.
• b, c and e do not match the pattern as 'the window' has o and w that is not included in the pattern. 'good' also has more than one character that is not included in the pattern. Similarly, will also have more than 1 character not included in the pattern.

4. none of these

• The text should have one or more characters of a followed by any single character from a to z. There does not include any + sign in between the text. Hence, the option a,b,d ,and e are incorrect.
• Also, option c is incorrect as it should minimum have 2 characters.

5. a and e

• The pattern should have a single character from a to z followed by one or more occurrences of characters from a to z and + as a symbol.
• Option b is incorrect as it starts with + symbol and not with any character from a to z.
• Option c is incorrect as there should be at least 2 characters.
• Option d is incorrect 1 is included which is not a part of the regex.

6. a,c and d

• The text should start from a and then followed by any character except newline and followed by one or more characters of b and c. Hence, it should start from a and end with the combination of b or c.
• Option b is not correct as it ends with z. Option e is also incorrect as it ends with z.

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