regular expression [^ ] Post: 302206088

Sponsored Content

Top Forums Shell Programming and Scripting regular expression [^ ] Post 302206088 by sonam on Tuesday 17th of June 2008 02:37:38 AM

06-17-2008

Registered User

Actually regular expression support is not uniform in all languages. Perl compatible regular expressions (also called PCRE) are a very common set of regular expressions compatible with how Perl supports regular expressions. Regular expression support in the webMethods 'Flow' language is not explicitly stated as PCRE according to their documentation (but may be).

The original poster may have been asking about this statement from an article here: (because I hit this forum when researching the same topic)
--
Regular Expressions for Integration Server
wMUsers: For webMethods Professionals -- Knowledge Base | Regular Expressions for Integration Server
--

/[^ ]/ -- [matches a variable that is] is not null, is not empty, and contains at least one non-space character.

My question was also similar - how come this does _not_ match the empty string, or null? I think the answer is a square bracket pair ('[...]') must match some character, and the '^ ' just excludes the space character from matching. Is this correct?

I modified the Perl code helpfully posted earlier, by adding an empty string ("") as the last case:

Code:

#!/usr/bin/perl

@t = ('m', "\t", '1', " ", "\n","");
for my $i (0..$#t) {
    if ($t[$i] =~ /[^ ]/) {
       print qq{Number $i is true "$t[$i]"\n};
    } else {
       print qq{Number $i is NOT true "$t[$i]"\n};
    }
}

Running this, I get these results:

Code:

Number 0 is true "m"
Number 1 is true "      "
Number 2 is true "1"
Number 3 is NOT true " "
Number 4 is true "
"
Number 5 is NOT true ""

So does result #5 confirm my understanding above --- the square bracket pair ('[...]') _must_ match some character, and the '^ ' just excludes the space character from matching.

sonam

View Public Profile for sonam

Find all posts by sonam

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Regular Expression + Aritmetical Expression

Is it possible to combine a regular expression with a aritmetical expression? For example, taking a 8-numbers caracter sequece and casting each output of a grep, comparing to a constant. THX!

2. Programming

What does the regular expression ['(^[^~]+~).*'] mean?

What does the regular expression +~).*'] mean while using it with regexec.When the string "RCHNUSNT35C~rs07/ASM-RS07" is used with the regular expression +~).*'] regexec gives an error. I know what regexec does,but i do not understand what this expression means wrt to this string... any help...

3. Linux

Regular expression to extract "y" from "abc/x.y.z" .... i need regular expression

Regular expression to extract "y" from "abc/x.y.z"

4. UNIX for Dummies Questions & Answers

ls with regular expression

I currently list and sort all the files in a directory which begin with an Upper Case C and end with the extension '#finished#'. Here is the command I use: ls -tr $currentDir/*.#finished# what i need to do now is list all the files in a directory that begin with upper case C and end...

5. Shell Programming and Scripting

Integer expression expected: with regular expression

CA_RELEASE has a value of 6. I need to check if that this is a numeric value. if not error. source $CA_VERSION_DATA if * ] then echo "CA_RELESE $CA_RELEASE is invalid" exit -1 fi + source /etc/ncgl/ca_version_data ++ CA_PRODUCT_ID=samxts ++ CA_RELEASE=6 ++ CA_WEEK_NO=7 ++...

6. Programming

Perl: How to read from a file, do regular expression and then replace the found regular expression

Hi all, How am I read a file, find the match regular expression and overwrite to the same files. open DESTINATION_FILE, "<tmptravl.dat" or die "tmptravl.dat"; open NEW_DESTINATION_FILE, ">new_tmptravl.dat" or die "new_tmptravl.dat"; while (<DESTINATION_FILE>) { # print...

7. UNIX for Advanced & Expert Users

sed: -e expression #1, char 0: no previous regular expression

Hello All, I'm trying to extract the lines between two consecutive elements of an array from a file. My array looks like: problem_arr=(PRS111 PRS213 PRS234) j=0 while } ] do k=`expr $j + 1` sed -n "/${problem_arr}/,/${problem_arr}/p" problemid.txt ---some operation goes...

8. UNIX for Dummies Questions & Answers

Regular expression help

Hi, I am quite knew to scripting and I am trying to get a regular expression to work to check that a user enters a valid version number such as 1 or 1.1 or 12.3 etc. I dont seem to be able to get it to work as it picks up versions such as 1.......2. I only want it to work with a single dot....

9. Shell Programming and Scripting