Let us see some important Regular expression Solved Exercises.

## Regular expression of strings begin with 110

**R.E= 110(0+1)***

## DFA of the language begins with 110

**Accepted String**

- Strings of length 1 = (Nil)
- Strings of length 2 = (Nil)
- Strings of length 3 = (110, No more)
- Strings of length 5 = (11001, 11011, 11000, …and many more similar strings)
- Strings of length 7 = (1100101, 1101101, 1100011, …and many more similar strings)
- Strings of length 10= (1100101000, 1101101111, 1100011101, …and many more similar strings)
- Strings of length 15= (110010100011010, 110110111101110, 110001110100011, …and many more similar strings)
- and many more similar strings

**Rejected Strings**

- Strings of length 1 = (0, 1, no more)
- Strings of length 2 = (00, 11, 10, …and many more similar strings)
- Strings of length 3 = (010, 011, 101, …and many more similar strings)
- Strings of length 5 = (01011, 10100, 01001, …and many more similar strings)
- Strings of length 10= (0101111000, 1010000111, 0100110101, …and many more similar strings)
- Strings of length 15= (010111100011000, 101000011100011, 010011010101010, …and many more similar strings)
- and many more similar strings.

## Regular expression of strings begin and end with 110

**R.E= 110(0+1)*110**

**Accepted String**

- Strings of length 1 = (Nil)
- Strings of length 2 = (Nil)
- Strings of length 3 = (Nil)
- Strings of length 5 = ((Nil)
- Strings of length 6 = (110110)
- Strings of length 7 = (1100110, 1101110)
- Strings of length 8= (11000110, 11010110, …. and many more similar strings)
- Strings of length 10 = (1101010110, 1101000110, 1100100110, …. and many more similar strings)
- Strings of length 15= (110101011000110, 110100011010110, 110010011001110, …. and many more similar strings)
- and many more similar strings.

**Rejected Strings**

- Strings of length 1 = (0, 1, no more)
- Strings of length 2 = (00, 11, 10, 01)
- Strings of length 3 = (010, 011, 101, …. and many more similar strings)
- Strings of length 5 = (01011, 10100, 01001, …. and many more similar strings)
- Strings of length 7 = (0110101, 1010011, 0011001, …. and many more similar strings)
- Strings of length 8= (11000011, 11010111, …. and many more similar strings)
- Strings of length 10 = (1101010010, 1101000101, 1100100100, …. and many more similar strings)
- Strings of length 15= (010101011000110, 000100011010110, 110010011000010, …. and many more similar strings)
- and many more similar strings.

## Regular expression of strings containing exactly three consecutive 1’s

**R.E= (0+1)*111(0+1)***

**Accepted String**

- Strings of length 1 = (Nil)
- Strings of length 2 = (Nil)
- Strings of length 3 = (111, no string)
- Strings of length 5 = (11100, 11101, 11111, …. and many more similar strings)
- Strings of length 7 = (1110001, 1110100, 1110001, , …. and many more similar strings)
- Strings of length 10 = (1110001110, 1110100111, 1110000011, …. and many more similar strings)
- Strings of length 15= (111000111000011, 111010011101110, 111000001101011, …. and many more similar strings)
- and many more similar strings.

**Rejected Strings**

- Strings of length 1 = (0, 1)
- Strings of length 2 = (00, 01, 10, 11)
- Strings of length 3 = (001, 011, 000, …. and many more similar strings)
- Strings of length 5 = (01101, 00111, 11000, …. and many more similar strings)
- Strings of length 7 = (0110100, 0110111, 1100011, …. and many more similar strings)
- Strings of length 10= (0110100, 0110111, 1100011, …. and many more similar strings)
- Strings of length 15= (011010011100, 011011100011, 101001101100, …. and many more similar strings)
- and many more similar strings.

## Download Slides Presentation PPT

Regular expression Solved Exercises PPT

## More Examples of Regular Expression

- Regular Expression for no 0 or many triples of 0’s and many 1 in the strings.
- RegExp for strings of one or many 11 or no 11.
- Regular expressions for all non empty strings
- Regular expressions over {a, b} for all non empty strings of even length
- Regular expressions for all non empty strings of odd length
- A regular expression for ending with abb
- A regular expression for all strings having 010 or 101.
- Regular expression for Even Length Strings defined over {a,b}
- Regular Expression for strings having at least one double 0 or double 1.
- Regular Expression of starting with 0 and having multiple even 1’s or no 1.
- Regular Expression for an odd number of 0’s or an odd number of 1’s in the strings.
- Regular Expression for having strings of multiple double 1’s or null.
- Regular Expression (RE) for starting with 0 and ending with 1.
- RE for ending with b and having zero or multiple sets of aa and bb.
- A regular expression of the second last symbol is 1.
- RE for starting with 1 having zero or multiple even 1’s.
- Regular Expression for multiple a’s and multiple b’s.
- RE for exactly single 1 many 0’s |exactly single a many b.
- A regular expression for strings starting with aa and ending with ba.
- A regular expression for the language of all consecutive even length a’s.
- A regular expression for the language of all odd-length strings
- A regular expression for the language of all even length strings but ends with aa.
- A regular expression for the language of an odd number of 1s.
- A regular expression for the language of even length strings starting with a and ending with b in theory of automata.
- A regular expression for the language of all even length strings but starts with a.
- A Regular Expression for the Language of all strings with an even number of 0’s or even number of 1’s.
- A regular expression for the language of all those strings end with abb.
- A regular expression for string having must 010 or 101.
- Regular expression of strings begin with 110

Regular expression of strings begin and end with 110

Regular expression of strings containing exactly three consecutive 1’s. - A Regular Expression of all strings divisible by 4.
- A Regular Expression Strings that does not contain substring 110.
- Regular expressions for all strings with at least one a
- Regular expressions for all strings with at least two a’s
- Regular expressions for All strings with exactly two b
- Regular expressions for at least one a and at least one b
- Regular expression form end in a double letter (two a’s or two b’s)
- Regular expression for All strings containing exactly one a

## Tutorial: Regular Expression

A detailed tutorial of the regular expression is here in the link of regular expression tutorial. This page contains the practice questions of regular expressions with solutions.

**Tutorial covering the topics**

- Give a regular expression.
- Describe the strings of the regular expression.
- write a regular expression.
- create all strings from regular expression.
- Generate all strings from regular expression.
- Extract all strings from regular expression.
- Find all strings from regular expression.
- Examples of regular expression.