use rand::seq::SliceRandom; // shuffle
use rand::rng; // thread-local random generator (rand 0.9+)
/*
A standard deck of 52 playing cards consists of four suits:
spades (♠), hearts (♥), diamonds (♦), and clubs (♣).
Each suit contains 13 ranks:
Ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, King.
Cards of spades and clubs are black, while hearts and diamonds are red.
Color is informational only — it does not affect shuffling or random selection.
*/
/*
This program picks 5 random cards from a standard 52-card deck.
It uses:
- Vec<String> for the deck
- SliceRandom::shuffle for efficient randomization
- rand::rng() as the high-quality, thread-local random source
*/
// Builds a standard 52-card deck as a vector of "Rank of Suit" strings.
fn build_deck() -> Vec<String> {
// Ranks and suits of a standard deck
let ranks = [
"2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K", "A",
];
let suits = ["Clubs", "Diamonds", "Hearts", "Spades"];
let mut deck = Vec::with_capacity(52); // Efficient: avoid reallocations
// Build the deck: 13 ranks x 4 suits
for suit in suits {
for rank in ranks {
deck.push(format!("{} of {}", rank, suit));
}
}
deck
}
fn main() {
// Build the deck
let mut deck = build_deck();
// Thread-local random generator, seeded securely by the OS
let mut rand_gen = rng();
// Shuffle the whole deck in place (Fisher-Yates, O(n))
deck.shuffle(&mut rand_gen);
// Draw the first 5 cards
println!("Your 5 random cards:");
for card in deck.iter().take(5) {
println!("{}", card);
}
}
/*
run:
Your 5 random cards:
10 of Clubs
Q of Diamonds
3 of Clubs
Q of Clubs
K of Spades
*/
