String::Random(3pm) User Contributed Perl Documentation String::Random(3pm)NAMEString::Random - Perl module to generate random strings based on a
pattern
SYNOPSIS
use String::Random;
my $string_gen = String::Random->new;
print $string_gen->randregex('\d\d\d'); # Prints 3 random digits
# Prints 3 random printable characters
print $string_gen->randpattern("...");
or
use String::Random qw(random_regex random_string);
print random_regex('\d\d\d'); # Also prints 3 random digits
print random_string("..."); # Also prints 3 random printable characters
DESCRIPTION
This module makes it trivial to generate random strings.
As an example, let's say you are writing a script that needs to
generate a random password for a user. The relevant code might look
something like this:
use String::Random;
my $pass = String::Random->new;
print "Your password is ", $pass->randpattern("CCcc!ccn"), "\n";
This would output something like this:
Your password is UDwp$tj5
NOTE!!!: currently, String::Random uses Perl's built-in predictable
random number generator so the passwords generated by it are insecure.
If you are more comfortable dealing with regular expressions, the
following code would have a similar result:
use String::Random;
my $pass = String::Random->new;
print "Your password is ",
$pass->randregex('[A-Z]{2}[a-z]{2}.[a-z]{2}\d'), "\n";
Patterns
The pre-defined patterns (for use with "randpattern()" and
"random_pattern()") are as follows:
c Any Latin lowercase character [a-z]
C Any Latin uppercase character [A-Z]
n Any digit [0-9]
! A punctuation character [~`!@$%^&*()-_+={}[]|\:;"'.<>?/#,]
. Any of the above
s A "salt" character [A-Za-z0-9./]
b Any binary data
These can be modified, but if you need a different pattern it is better
to create another pattern, possibly using one of the pre-defined as a
base. For example, if you wanted a pattern "A" that contained all
upper and lower case letters ("[A-Za-z]"), the following would work:
my $gen = String::Random->new;
$gen->{'A'} = [ 'A'..'Z', 'a'..'z' ];
or
my $gen = String::Random->new;
$gen->{'A'} = [ @{$gen->{'C'}}, @{$gen->{'c'}} ];
The random_string function, described below, has an alternative
interface for adding patterns.
Methods
new
new max => number
new rand_gen => sub
Create a new String::Random object.
Optionally a parameter "max" can be included to specify the
maximum number of characters to return for "*" and other
regular expression patterns that do not return a fixed number
of characters.
Optionally a parameter "rand_gen" can be included to specify a
subroutine coderef for generating the random numbers used in
this module. The coderef must accept one argument "max" and
return an integer between 0 and "max - 1". The default
rand_gen coderef is
sub {
my ($max) = @_;
return int rand $max;
}
randpattern LIST
The randpattern method returns a random string based on the
concatenation of all the pattern strings in the list.
It will return a list of random strings corresponding to the
pattern strings when used in list context.
randregex LIST
The randregex method returns a random string that will match
the regular expression passed in the list argument.
Please note that the arguments to randregex are not real
regular expressions. Only a small subset of regular expression
syntax is actually supported. So far, the following regular
expression elements are supported:
\w Alphanumeric + "_".
\d Digits.
\W Printable characters other than those in \w.
\D Printable characters other than those in \d.
. Printable characters.
[] Character classes.
{} Repetition.
* Same as {0,}.
? Same as {0,1}.
+ Same as {1,}.
Regular expression support is still somewhat incomplete.
Currently special characters inside [] are not supported (with
the exception of "-" to denote ranges of characters). The
parser doesn't care for spaces in the "regular expression"
either.
Functions
random_string PATTERN,LIST
random_string PATTERN
When called with a single scalar argument, random_string
returns a random string using that scalar as a pattern.
Optionally, references to lists containing other patterns can
be passed to the function. Those lists will be used for 0
through 9 in the pattern (meaning the maximum number of lists
that can be passed is 10). For example, the following code:
print random_string("0101",
["a", "b", "c"],
["d", "e", "f"]), "\n";
would print something like this:
cebd
BUGS
This is Bug FreeX code. (At least until somebody finds oneX)
Please report bugs here:
<https://rt.cpan.org/Public/Dist/Display.html?Name=String-Random> .
AUTHOR
Original Author: Steven Pritchard "steve@silug.org"
Now maintained by: Shlomi Fish ( <http://www.shlomifish.org/> ).
LICENSE
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
SEE ALSOperl(1).
perl v5.22.1 2015-12-26 String::Random(3pm)
