perhaps OP means the last 5 chars of the string must terminate with not more than 4 digits.
#!C:/perl/bin -w =head I want a regular expression that checks that a string has only 4 digit +s at the end & starts with "aaa_", inbetween string can have digits,a +lphabets and underscore{1,24} . ... Please provide a regexp that says: Match for "aaa_gjh1_dfgdf_0009","aaa_gjh_0000" No Match for "aaa_fdsfs_000", "aaa_sdf_jdsh_01111". i.e. allows ONLY 4 digits at the end of a string =cut my @testitems = qw( aaa_gjh1_dfgdf_0009 aaa_gjh_0000 aaa_gjh1_DFgdf_0009 aaa_gjh_0000 aaa_fdsfs_000 aaa_sdf_jdsh_01111 aaa_gjh1_dfgdf_0009 aaa_gjh1_df<:df_0009 aaa_gjh_0000 aaa_fdsfs_000 ); for my $item(@testitems) { if ( $item =~ m/ ^aaa_ # starts with "aaa_" [_A-Za-z0-9]{1,23} # test next 1,23 chars: underline, alpha or dec +imal_nums (?<=\D) # Positive_Lookbehind, Last char BEFORE last 4 # (potentially, the 24th) # can't be a digit else we may find 5 digit +s at the end \d{4}$ # has ONLY - emphasis mine - four digits at the + end /x ) { print "Matches: $item\n"; } else { print "\tNo match: $item\n"; } } print "done\n"; =head1 OUTPUT: Matches: aaa_gjh1_dfgdf_0009 Matches: aaa_gjh_0000 Matches: aaa_gjh1_DFgdf_0009 Matches: aaa_gjh_0000 No match: aaa_fdsfs_000 No match: aaa_sdf_jdsh_01111 Matches: aaa_gjh1_dfgdf_0009 No match: aaa_gjh1_df<:df_0009 Matches: aaa_gjh_0000 No match: aaa_fdsfs_000 done =cut

In reply to Re^2: Number of digits at the end of the string by ww
in thread Number of digits at the end of the string by isha

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.