Question

. Give an example of a string represented by each of the following regular expressions

• 0+ 1+ (11)* 0?

• [0-9]+ ( (E|e) (\+|\-)? [0-9]+ )?

• ([a..z] ([a..z] | [0..9])*)

Answer 1

Examples of the various string generated by the following regular expressions:

• Regular Expression sign and meaning:

* = Zero or more occurrences

+ =  One or more occurrences

? = Zero or One occurrence

| = Logical OR

[..] = Any one character from specified range

(..) = All characters from specified range

\ = Escape sequence (\+ matches the with special character +)

(1)  0+ 1+ (11)* 0?

Example String: 01110  

Other Examples:

• 010

• 01

• 0111110

• 0111

(If regular expression is not having free-spacing mode then string would look like: 0 1 11 0)

(2) [0-9]+ ( (E|e) (\+|\-)? [0-9]+ )?

Example String: 1004E+68

Other Examples:

• 1234

• 88e-7684

• 44E+1234

• 9999e+44

(If regular expression is not having free-spacing mode then string would look like: 1004 E + 68)

(3)  ([a..z] ([a..z] | [0..9])*)

Example String: m9

Other Examples:

• rddd

• h4444

• abcd9

• hello4

(If regular expression is not having free-spacing mode then string would look like: m 9)