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How can I check if a Perl string contains letters?

开发者 https://www.devze.com 2022-12-15 23:43 出处:网络
In Perl, what regex should I use to find if a string of characters has letters or not? Example of a string used: Thu Jan1 05:30:00 1970

In Perl, what regex should I use to find if a string of characters has letters or not? Example of a string used: Thu Jan 1 05:30:00 1970

Would this be fine?

    if ($l =~ /[a-zA-Z]/)
 {
    print "string ";    
 开发者_如何学编程}
 else
 {      
    print "number ";    
 }


try this:

/[a-zA-Z]/

or

/[[:alpha:]]/

otherwise, you should give examples of the strings you want to match.

also read perldoc perlrequick

Edit: @OP, you have provided example string, but i am not really sure what you want to do with it. so i am assuming you want to check whether a word is all letters, all numbers or something else. here's something to start with. All from perldoc perlrequick (and perlretut) so please read them.

sub check{
    my $str = shift;
    if ($str =~ /^[a-zA-Z]+$/){
        return $str." all letters";
    }
    if ($str =~ /^[0-9]+$/){
        return $str." all numbers";
    }else{
        return $str." a mix of numbers/letters/others";
    }
}

$string = "99932";
print check ($string)."\n";
$string = "abcXXX";
print check ($string)."\n";
$string = "9abd99_32";
print check ($string)."\n";

output

$ perl perl.pl
99932 all numbers
abcXXX all letters
9abd99_32 a mix of numbers/letters/others


If you want to match Unicode characters rather than just ASCII ones, try this:

#!/usr/bin/perl

while (<>) {
  if (/[\p{L}]+/) {
    print "letters\n";
  } else {
    print "no letters\n";
  }
}


If you're looking for any kind of letter from any language, you should go with

\p{L}

Take a look on this full reference: Unicode Character Properties


Using /[A-Za-z]/ is a US-centric way to do it. To accept any letter, use one of

  • /[[:alpha:]]/
  • /\p{L}/
  • /[^\W\d_]/

The third one employs a double-negative: not not-a-letter, not a digit, and not an underscore.

Whichever you choose, those who maintain your code will certainly appreciate it if you stick with one consistently!


If you're looking to detect whether something looks like a number for the purposes of manipulating it in Perl, you'll want Scalar::Util::looks_like_number (core since perl 5.7.3). From perlapi:

looks_like_number

Test if the content of an SV looks like a number (or is a number). Inf and Infinity are treated as numbers (so will not issue a non-numeric warning), even if your atof() doesn't grok them.


[^\W0-9_]

# or

[[:alpha:]]

See perldoc perlre

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