Raku Books / Using Raku / Strings / Modifying string data

9. Random passwords

Generate a random string that can be used as a password.

One of the possible solutions looks like this:

say ('0' .. 'z').pick(15).join('');

The pick method with no arguments takes a random element from the range of the ASCII characters between 0 and z. In the above example, calling pick(15) selects 15 different characters, which are then joined together using the join method.

It is important to know the two key features of the pick method. First, when called with an integer argument bigger than 1, the result contains only unique elements. Thus, all the characters in the password are different.

The second feature is a consequence of the first one. If the provided list of elements is not long enough, and its length is less than the argument of pick, the result is as long as the original data list.

To see which elements are used for generating a password, run the code with a number bigger than the whole ASCII sequence:

say ('0' .. 'z').pick(1000).sort.join('');

With this request, you will see all the characters that participate in forming a random password:

0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`
abcdefghijklmnopqrstuvwxyz

An example of a generated password: 05<EV]^bdfhnpyz.

To limit the character range, list the characters you want to see in a password:

my @chars = '0' ... '9', 'A' ... 'Z', 'a' ... 'z';
say @chars.pick(15).join('');

Now the password only contains alphanumeric symbols: 2zOIySp5PHb08Ql.

The ... operator creates a sequence. Be warned not to use the .. operator, which creates a range, in which case the @chars array is an array of ranges rather than a flat array of single characters.

The solution is quite elegant and does not require explicit use of the rand function. Neither loops are needed.

Now, let us solve the task in such a way that characters may be repeated in the result. It is still possible to use the pick method but it should be called independently a few times.

my $password = '';
$password ~= ('0' .. 'z').pick() for 1..15;
say $password;

Now, the password can include the same character more than once, for example: jn@09Icoys@tD;o.

To get the string of unique characters, use the pick method instead of roll. When using roll, you have to make sure the source list of characters is bigger than the length of your password.

my $password = '';
$password ~= ('0' .. 'z').roll() for 1..15;
say $password;

Run the code a few times to confirm that you generate good passwords that are all different and do not contain the same characters more than once.

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9. Random passwords

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