Matching strings without repeated spaces

Discussion in 'Perl Misc' started by usenet, Jun 23, 2006.

  1. usenet

    usenet Guest

    I want to construct a regexp which will match a string containing only
    \w and \s, but not repeated whitespaces. I can do it (crudely) with
    two regexps, such as:

    if (/[\w\s-]+$/ && ! /\s\s/) {

    but I'd rather do it with a single regexp... but guessing at the syntax
    has not proved effective.

    I'd appreciate some insight...

    usenet, Jun 23, 2006
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  2. Then you should anchor _both_ ends of the pattern.

    Use a negative lookahead assertion:

    if ( /^(\w+|\s(?!\s))+$/ ) {

    or, written for human consumption:

    if ( /^ (
    ) {
    Tad McClellan, Jun 23, 2006
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  3. usenet

    Xicheng Jia Guest

    how about this

    if (/^(?:\w\s?)*$/) { ... }

    Xicheng Jia, Jun 23, 2006
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