If the regex does not have an x modifier, just use a literal space. If it does have an x modifier, put the space into a character class:

13:26 >perl -wE "my $s = 'a b'; say 'matched' if $s =~ /a b/;"
matched

14:47 >perl -wE "my $s = 'a b'; say 'matched' if $s =~ /a[ ]b/x;"
matched

14:47 >
[download]

Hope that helps,

say I have two arrays , arrayA and arrayB . and I wish to print something like this

print " \s $arrayA[$i] \s $arrayB[$i] \s";
[download]

I have assumed that \s is giving space , so I just want , what should i replace $s with ?

If that's what you want to print, you don't need any space regex.

print " $arrayA[$x] $arrayB[$x] ";

will print the spaces too...

I hope that helps.

-Michael

$var1." ".$var2;

If you use use strict; use warnings; you will probably find an error in this statement that has nothing to do with spaces. I suspect that you intend $i to be a subscript. If so,

print " $arrayA[$i] $arrayB[$i] ";
[download]

Note: \s is special character class for regular expressions. It does not have the same meaning in a string. Just use space characters.
Bill

See "Escape sequences" and "Character Classes and other Special Escapes" in perlre - Regular Expressions.

For a more in-depth discussion see "Whitespace" in perlrecharclass - Backslash sequences.

There is also perlrebackslash - Perl Regular Expression Backslash Sequences and Escapes
\040 Octal escapes
\x20 or \x{20} Hexadecimal escapes
\N{U+0020} or \N{SPACE} Named or numbered characters and character sequences
[ ] Character classes
(?-x: ) (?adlupimsx-imsx:pattern)

\x20

---

s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

Under most circumstances, spaces don't need to be escaped. Just use a literal space.

In the few cases where it does need to be escaped, the appropriate escape sequence depends on which case you're dealing with, so there's no single, universal answer. You'll need to specify the context in which you're escaping the space.