representing a string with Regular Expressions (resolved)

As part of an assignment I am trying to represent a string with RE which stands for regular expressions. The string is delimited by double quotes. It can have newline characters at the end. I was wondering if anyone might give me some feedback on if its correct and how to handle the newline characters.

I have this so far:

String Literals with RE
( " ) ( 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 ) | ( a | b | c | d | e | f | g | h | i | j | k | l | m | n | o | p | q | r | s | t | u | v | w | x | y | z ) ( 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 )*
( a | b | c | d | e | f | g | h | i | j | k | l | m | n | o | p | q | r | s | t | u | v | w | x | y | z )* (newlines will go here) (")

Anyone know how I can put in newlines and if the rest is correct?

Well the regular expression you have just posted would match a string like this:

"f48494990434668646758ndrk\r\n"

\r\n = New Line

The regular expression you wrote is similar to saying. Match a string whose first character is a double quotation, the second is a numerical character between 0 and 9 or a lower case letter followed by zero or more numerical characters between 0 and 9 followed by zero or more lower case characters. The string must end in with a double quotation and a newline.

Rather than writing all the letters and numbers you could do this:

/ "([0-9] | [a-z])[0-9]*[a-z]*"$ /

The $ symbol mathes the end of line character. Where as [a-z] is a character class representing a range of characters.

My regular expression is supposed to represent any string and the string is delimited by ". It can end with a newline character. Its right I think my question is How do I represent a newline character at the end of the string? I cant use [] $ or other extended RE notation.

Quote:

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Originally posted by abcdefg
My regular expression is supposed to represent any string and the string is delimited by ". It can end with a newline character. Its right I think my question is How do I represent a newline character at the end of the string? I cant use [] $ or other extended RE notation.

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It depends on what characters your string can contain. If it is just letters and numbers then a simple:

Code:

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((( 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 ) | ( a | b | c | d | e | f | g | h | i | j | k | l | m | n | o | p | q | r | s | t | u | v | w | x | y | z ) | (A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z))*")+(\n | (\r\n))

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The RE above will match an number of alpha-numeric strings delimited by quotes. \n matches a UNIX style newline and \r\n matches a Wdinwos style newline.

If you want to match a string which includes any ascii character It would be a little more complicated.

thanx got it