Can a Perl regexp validate arithmetic expressions? I say yes. Here is my Perl regexp to validate arifmetic expressions:
Code:
#!perl -w
use strict;
use re 'eval';
my @testexpr=(
# Valid arifmetic expressions
'+3',
'-(3/4+(-2-3)/3)',
'(-((3)))',
'-(+1+2)*(3/(1-2))/((-3))',
# Invalid (from the point of view of a human) arifmetic expressions
'2*-3',
'-(3/4+(-2-3)/3',
'(-((3)+))');
my $number=qr/\d+/; # pattern for a digit/variable
my $arifm;
# The modifier x is used to split the regexp to publish it in Web
$arifm=qr#[+-]?(?:$number|\((??{$arifm})\))(?:[*/](?:$number|\((??{$arifm})\)))*
(?:[+-](?:$number|\((??{$arifm})\))(?:[*/](?:$number|\((??{$arifm})\)))*)*#x;
print /^$arifm$/ ? "Valid: $_\n" : "Invalid: $_\n" for (@testexpr);
I need help with a Perl regular expression.
The following string blows up my program: <david(greg jim)>
If I type this string, there is no problem: <david(greg_jim)> or type
david(gregjim) or type <david greg jim> the CGI program does not complain.
For some reason that I do not understand the... (1 Reply)
I am writing script that will act like the 'comm' utility. My
problem is when trying to read whether the user has entered -123 or -1
or -1...etc.
I currently have:
if(m/??/g){
print "Good.\n";
}
So, this should check for all... (1 Reply)
What is the easiest way to get full address of *.jpg images from html file using perl?
example:
http://farm3.static.flickr.com/2397/2126443111_65a810004c.jpg (1 Reply)
Hello,
$line=USING (FILE '/TEST1/FILENAME'5000)
I want to reterive the value between ' and ) which is 5000 here.
i have tried out the following expressions ...
Type 1 : $Var1=`sed -e 's/.*\' //' -e 's\).*$/' $line`;
Type 2 : $Var1=`echo $line | awk -F"\'" '{print $2}' | awk -F"\\)"... (1 Reply)
Hello everybody,
I am trying to connect from hp-ux to win 2003 using perl's Net::Telnet module. Seeing the examples in couple of web sites, I saw I have to declare a Prompt =>
Can somebody please tell me what my regular expression should be? The prompt after I log in is:
...
login:... (1 Reply)
Hello,
I cannot see what's wrong in my code.
When I run code below, it just print an empty string.
my $test = "SWER~~ERTGSDFGTHAS_RTAWGA_DFAS.x4-234253454.in";
if ($test = ~ m/\~{1,2}.*4/) {
print "$1\n";
}
else {
print "No match...\n";
}
Anyone know what I'm doing wrong?
... (4 Replies)
Hi. Here's a tricky one (at least to me):
I have a file named theFile.txt (UTF-8) that contains the following:
a
b
cWhen I execute
perl -pe 's|a.*c|d|sg' theFile.txtin bash 3.2 on MAC OS X 10.6, I get no match, i.e. the result is
a
b
cagain. Any clues why? (2 Replies)
im trying to extract some tags between and in a file..for eg..the file format is
I want the and extracted from the file i.e the tags which is present b/w and
I have the regex for extracting the tags from the whole file but how to specify my search within the and... (1 Reply)
Hi,
I am trying with the below Perl one-liner using regular expression to extract the first and second column of a text file:
perl -p -e "s/\s*(\w+).*/$1/"
perl -p -e "s/\s*.+\s(.+)\s*/$1\n/"
whereas the text file's data looks like:
Error: terminated 2233
Warning: reboot 3434
Warning:... (3 Replies)
Discussion started by: royalibrahim
3 Replies
LEARN ABOUT SUSE
trim
textutil::trim(n) Text and string utilities, macro processing textutil::trim(n)
__________________________________________________________________________________________________________________________________________________NAME
textutil::trim - Procedures to trim strings
SYNOPSIS
package require Tcl 8.2
package require textutil::trim ?0.7?
::textutil::trim::trim string ?regexp?
::textutil::trim::trimleft string ?regexp?
::textutil::trim::trimright string ?regexp?
::textutil::trim::trimPrefix string prefix
::textutil::trim::trimEmptyHeading string
_________________________________________________________________DESCRIPTION
The package textutil::trim provides commands that trim strings using arbitrary regular expressions.
The complete set of procedures is described below.
::textutil::trim::trim string ?regexp?
Remove in string any leading and trailing substring according to the regular expression regexp and return the result as a new
string. This is done for all lines in the string, that is any substring between 2 newline chars, or between the beginning of the
string and a newline, or between a newline and the end of the string, or, if the string contain no newline, between the beginning
and the end of the string. The regular expression regexp defaults to "[ \t]+".
::textutil::trim::trimleft string ?regexp?
Remove in string any leading substring according to the regular expression regexp and return the result as a new string. This apply
on any line in the string, that is any substring between 2 newline chars, or between the beginning of the string and a newline, or
between a newline and the end of the string, or, if the string contain no newline, between the beginning and the end of the string.
The regular expression regexp defaults to "[ \t]+".
::textutil::trim::trimright string ?regexp?
Remove in string any trailing substring according to the regular expression regexp and return the result as a new string. This apply
on any line in the string, that is any substring between 2 newline chars, or between the beginning of the string and a newline, or
between a newline and the end of the string, or, if the string contain no newline, between the beginning and the end of the string.
The regular expression regexp defaults to "[ \t]+".
::textutil::trim::trimPrefix string prefix
Removes the prefix from the beginning of string and returns the result. The string is left unchanged if it doesn't have prefix at
its beginning.
::textutil::trim::trimEmptyHeading string
Looks for empty lines (including lines consisting of only whitespace) at the beginning of the string and removes it. The modified
string is returned as the result of the command.
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category textutil
of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for
either package and/or documentation.
SEE ALSO
regexp(n), split(n), string(n)
KEYWORDS
prefix, regular expression, string, trimming
textutil 0.7 textutil::trim(n)
12-06-2010
