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# Generating Random Numbers

## Problem

You want to make random numbers in a given range, inclusive, such as when you randomly pick an array index, simulate rolling a die in a game of chance, or generate a random password.

## Solution

Use Perl’s `rand` function.

`\$random = int( rand( \$Y-\$X+1 ) ) + \$X;`

## Discussion

This code generates and prints a random integer between 25 and 75, inclusive:

```\$random = int( rand(51)) + 25;
print "\$random\n";```

The `rand` function returns a fractional number, from (and including) up to (but not including) its argument. We give it an argument of 51 to get a number that can be or more, but never 51 or more. We take the integer portion of this to get a number from to 50, inclusive (50.99999.... will be turned to 50 by `int`). We then add 25 to it, to get a number from 25 to 75, inclusive.

A common application of this is the random selection of an element from an array:

`\$elt = \$array[ rand @array ];`

And generating a random password from a sequence of characters:

```@chars = ( "A" .. "Z", "a" .. "z", 0 .. 9, qw(! @ \$ % ^ & *) );
\$password = join("", @chars[ map { rand @chars } ( 1 .. 8 ) ]);```

We use `map` to generate eight random indices into `@chars`, extract the corresponding characters with a slice, and join them together to form the random password. This isn’t a good random number, though, as its security relies on the choice of seed, which is based on the time the program started. See Section 2.8 for a way to better seed your random number generator.

The `int`, `rand`, `map`, and ...